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Project no: 502687 NEEDS

New Energy Externalities Developments for Sustainability

INTEGRATED PROJECT Priority 6.1: Sustainable Energy Systems and, more specifically,

Sub-priority 6.1.3.2.5: Socio-economic tools and concepts for energy strategy.

Technical Report n° 4.1 - RS 2b “Additional technological advancements to be considered in

MCDA sensitivity analyses” Due date of deliverable: 20.12.2008 Actual submission date: 15.02.2009 Start date of project: 1 September 2004 Duration: 48 months Organisation name for this Technical Report: CESIRICERCA Technical Report coordinator: Antonio Negri Authors: Pierpaolo Girardi, Vittorio Brignoli, Claudio Casale, Fabrizio Paletta, Franco Polidoro, Mauro Scagliotti.

Project co-funded by the European Commission within the Sixth Framework Programme (2002-2006)

Dissemination Level PU Public

PP Restricted to other programme participants (including the Commission Services) X

RE Restricted to a group specified by the consortium (including the Commission Services)

CO Confidential, only for members of the consortium (including the Commission Services)

CONTENTS

1 INTRODUCTION 4

2 FOSSIL FUELS TECHNOLOGIES 5

2.1 TECHNOLOGIES CREDITED IN RS1A FOR 2030 – 2050. 5 2.1.1 MAIN DRIVERS INFLUENCING FUTURE FOSSIL TECHNOLOGY DEVELOPMENT 5 2.1.2 CO2 REDUCTION ONLY SCENARIO (BAU) 8 2.1.3 COAL GASIFICATION 9 2.1.4 CO2 CAPTURE SCENARIO 10 2.2 OPTINON :1 IGCC PLANTS 11 2.3 OPTION 2: PC OXYCOMB. 11 2.4 CONCLUSIONS: RESUME TABLES 13

3 FUEL CELLS 19

3.1 TECHNOLOGIES CREDITED IN RS1A FOR 2030 – 2050: BRIEF DESCRIPTION. 19 3.2 OPTION 1: HIGH TEMPERATURE PEFC 21 3.2.1 TECHNOLOGIES GAP DESCRIPTION 21 3.2.2 TECHNOLOGIES GAP INFLUENCES ON CRITERIA 22 3.3 OPTION 2: LARGER MCFC POWER SYSTEMS 23 3.3.1 TECHNOLOGIES GAP DESCRIPTION 23 3.3.2 TECHNOLOGIES GAP INFLUENCES ON CRITERIA 23 3.4 OPTION 3: INNOVATIVE SOFC 25 3.4.1 REVOLUTIONARY TECHNOLOGIES BREAK-THROUGHS DESCRIPTION 25 3.4.2 TECHNOLOGIES BREAK-THROUGHS INFLUENCES ON CRITERIA 25 3.5 CONCLUSION: RESUME TABLES 26

4 OFFSHORE WIND TECHNOLOGY 35

4.1 TECHNOLOGY CREDITED IN RS1A FOR 2025-2050 35 4.2 OPTION 1: SMALLER HORIZONTAL-AXIS WIND TURBINES 38 4.2.1 TECHNOLOGY GAP DESCRIPTION 38 4.2.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 38 4.3 OPTION 2: SMALLER VERTICAL-AXIS WIND TURBINES 39 4.3.1 TECHNOLOGY GAP DESCRIPTION 39 4.3.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 40 4.4 OPTION 3: SAME HORIZONTAL-AXIS WIND TURBINES ON FLOATING FOUNDATIONS 41 4.4.1 TECHNOLOGY GAP DESCRIPTION 41 4.4.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 42 4.5 OPTION 4: KITE VERTICAL-AXIS WIND TURBINES 42 4.5.1 TECHNOLOGY GAP DESCRIPTION 42 4.5.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 43 4.6 RESULTS OF COMPARISON OF THE FOUR TECHNOLOGICAL OPTIONS WITH THE BASELINE TECHNOLOGY ASSUMED FOR OFFSHORE WIND FARMS, IN RESPECT OF THE VARIOUS CRITERIA AND RELEVANT INDICATORS. 45 4.7 REFERENCES 49

5 PV TECHNOLOGY 50

5.1 TECHNOLOGY CREDITED IN RS1A FOR 2025-2050 50 5.2 PV MODULE TECHNOLOGY 51 5.3 OPTION 1: PESSIMISTIC SCENARIO, ROADMAP 3 OF THE REPORT RS1A 54 5.3.1 TECHNOLOGY GAP DESCRIPTION 54 5.3.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 55 5.4 OPTION 2: VERY OPTIMISTIC SCENARIO (ROADMAP 1 OF THE REPORT RS1A) 55 5.4.1 TECHNOLOGY GAP DESCRIPTION 55 5.4.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 56 5.5 OPTION 3: VERY OPTIMISTIC SCENARIO (EMERGING CONCEPTS) 56 5.5.1 TECHNOLOGY GAP DESCRIPTION 56 5.5.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 57 5.6 RESULTS OF COMPARISON OF THE TECHNOLOGICAL OPTIONS WITH THE BASELINE TECHNOLOGY ASSUMED FOR PV, IN RESPECT OF THE VARIOUS CRITERIA AND RELEVANT INDICATORS 58

6 SOLAR THERMAL POWER PLANTS 67

6.1 TECHNOLOGY CREDITED IN RS1A FOR 2025-2050 67 6.2 OPTION 1: THERMAL OIL PARABOLIC TROUGH SYSTEM WITH MOLTEN SALTS THERMAL STORAGE 74 6.2.1 TECHNOLOGY GAP DESCRIPTION 74 6.3 OPTION 2: POWER TOWER PLANT COUPLED WITH A LARGE MOLTEN SALTS THERMAL STORAGE 76 6.3.1 TECHNOLOGY GAP DESCRIPTION 76 6.4 OPTION 3: FRESNEL COLLECTOR POWER PLANT COUPLED WITH A LARGE THERMAL STORAGE BASED ON THE PHASE CHANGE MATERIAL. 78 6.4.1 TECHNOLOGY GAP DESCRIPTION 78 6.5 RESULTS OF COMPARISON OF THE TREE TECHNOLOGICAL OPTIONS WITH THE BASELINE SEGS ASSUMED, IN RESPECT OF THE VARIOUS CRITERIA AND RELEVANT INDICATORS. 80

7 NUCLEAR TECHNOLOGY 84

7.1 TECHNOLOGY CREDITED IN RS1A FOR 2025-2050 84 7.2 SELECTED OPTION : GAS FAST REACTOR 88 7.2.1 TECHNOLOGY GAP DESCRIPTION 88 7.2.2 TECHNOLOGY GAP INFLUENCE ON CRITERIA AND INDICATORS 89 7.3 RESULTS OF COMPARISON OF THE TECHNOLOGICAL OPTION WITH THE BASELINE ASSUMED, IN RESPECT OF THE VARIOUS CRITERIA AND RELEVANT INDICATORS 91 7.4 REFERENCES 102

1 Introduction One of the objective of the RS 2b of the IP NEEDS, is to address and evaluate sustainability of the candidate technologies or technology mixes for European electricity generation for the years 2025 an 2050. In order to evaluate the technologies sustainability, the RS 2b has taken into account their performance under economic, environmental and social criteria through a Multi-criteria decision analysis. The NEEDS Deliverable n° D3.1 – RS 2b “Environmental, economic and social criteria and indicators for sustainability assessment of energy technologies” describes the criteria used for the evaluation. The aim of the present reports is to provide further informations, beside those provided by RS 1a reports , on future innovative technologies for electricity generation. Those information are intended to be use as support to a sensitivity analysis for the Multi-criteria decision analysis. The technologies and technology mixes or scenarios credited from RS1a are, according to nowadays knowledge, the most likely to be implemented in years 2025 and 2050. For those technologies RS 1a provided complete LCAs while other information, i.e. economical, social and other environmental indicators have been quantified within the RS 2b. However it is clear that we are not sure that the technologies and technology mixes credited in RS 1a will be actually implemented and used in the reference years. In order to allow researchers and decision makers to understand how far the conclusion of the Multi-criteria decision analysis and the technologies rank are robust, we make some hypothesis on possible technologies gaps or breakthroughs that may occur in the next 15 – 40 years. “Ttechnology gap”, means small change in some characteristic (e.g. dimensions, efficiency…) that may strongly affect indicators. “Technology breakthrough” means a dramatic change in the way the electricity is produced from an energy source. In the following chapters we give a brief description of the technologies credited in RS 1a and, where significant, we describe possible future gap or breakthrough. As far as it was not possible to exactly quantify all indicators, we describe how and how far technology gaps and breakthroughs can have influence on indicators. The influence is described a qualitative way (by arrows) in for each indicators as described down here: �� no influence;� increase (about 50% or more); � small increase (about 30% or less); � small decrease (about 30% or less);� decrease (about 50% or more); The technologies for which we consider relevant and important to carry out this analysis are :

1. Fossil Fuels 2. Fuel cells 3. Offshore Wind 4. PV 5. Solar Thermal 6. Nuclear

The technologies has been chosen on the basis of the uncertainty of their development or on the basis of their supposed relevance in the future scenarios.

2 Fossil fuels Technologies Paolo Savoldelli, CESI RICERCA, SSG Department

2.1 Technologies credited in RS1a for 2030 – 2050. Coal is the fossil fuel with widest reserves worldwide. Construction of coal power plants has been steadily increased in fast developing countries like China and India. In Europe, since the early 1990s, the highly efficient combined cycle technology fuelled by natural gas has been successfully expanding to replace older fossil units (mainly oil-fuelled) and follow increasing electricity demand. However, taking into account the expected grow of electricity demand in Europe, coal may continue to play an important role in the energy mix besides natural gas. In order to obtain long term acceptability of coal, near-zero emissions requirements will likely become a goal for policy and technology improvement, first in highly industrialised countries and then also in developing ones. Worldwide research on Clean Coal Technology (CCT) pursues the satisfactorily environmental and economical utilisation of coal. Many of the conventional technologies of today can be further improved or refurbished with effective pollution control technologies. CO2 capture for sequestration is an extreme option in line with zero-emission strategy that may be implemented for some power plant technologies. There are some challenges that coal is facing: • curbing or virtually eliminating emissions of pollutants such as particulate matter and oxides of sulphur

and nitrogen. This has largely been achieved and costs are decreasing, but implementation should be continued to as many units as possible and extended to as many countries as possible, if compliance were required with more restrictive national emission (or air/water quality) standards.

• increasing thermal efficiency in order to reduce CO2 and other emissions per unit of net electricity supplied to the network. Efficiency of modern technology has been significantly increasing but there is still potential for further improvements.

• reducing or nearly eliminating CO2 emissions. Additionally, the coal industry is also promoting the vision of clean coal as a possible source of hydrogen or liquid fuels for stationary and transport applications too.

2.1.1 Main drivers influencing future fossil technology development The main driver for future fossil technology development is the demand for cheap, large-scale electricity generation. However, the demand for individual fossil technologies is not only driven by economy; also other factors, like the suitability to meet a likely growing demand, the need of environmentally sound performance, public acceptance, use of domestic resources, availability and security of supply of fuels and the need for fast responding capacity for network management are very important or key parameters. In the following, the focus will be limited to coal and natural gas, since already today oil is of minor importance for electricity production in Europe and it is expected to further decrease in the EU market. For fossil power generation, the fuel cost is amongst the factors with the highest influence on total electricity production costs. Unfortunately, estimations for future fuel prices are very difficult and quite uncertain. Different scenarios on the development of fossil fuel prices are presented in EC2004. While the coal price remains fairly constant until 2030, gas prices are considerably varied in those scenarios. In the “Baseline scenario”, the GDP in EU-25 is projected to grow at a rate of: • 2.5% per annum in 2000-2010; • 2.4% in 2010-2020; • 2.3% in 2020-2030

In this scenario gas prices are slightly increasing, which nevertheless does not reflect the quickly rising prices during last years. Taking into account the expected world-wide rising demand for both natural gas and coal, more limited global gas resources, and higher uncertainties concerning Europe’s gas supply, an increasing difference between gas and coal prices seems to be a realistic development. The influence of fuel cost on electricity production costs is higher for natural gas plants than for conventional coal steam plants. Higher costs for natural gas would favour coal technology deployment and development, as R&D for coal systems could be considered a better long-term investment. However, high natural gas prices also promote more rapid development and adoption of new energy efficient natural gas technologies, foster greater investment in exploration and field development, which helps to keep prices down. Within a shorter time horizon, since gas power plants are more flexible and can provide middle and peak load (marketable at higher prices than base load in soma circumstances), they may secure higher specific revenues than coal, which constitute another incentive for developing gas systems. Apart from nuclear and renewable sources, the most promising candidates for new capacity for electricity supply are both coal and natural gas. Anyhow, only coal and gas technologies, current as well as in 2025 and 2050 are dealt with within RS1. According to NEEDS project purposes, only some application will be addressed herein and namely large power generation systems fed by coal or natural gas. In principle, all the available technologies could be used for future applications, including those actually at early developing stage. In particular, Fuel Cells plants suitable for high stationary power (subject of another chapter in NEEDS report), should be taken into account in long term scenarios. Nevertheless all the chosen technologies (but oxy-combustion systems considered in the CO2 mandatory capture scenario) are presently in a mature or quite mature stage. Oxy-combustion systems and related technologies are not yet ready for market entry and only first demonstration programmes are currently ongoing worldwide. In the RS1a Report possible future developments and changes in terms of rated power, investment cost and electric efficiency are analysed referring to baseline and alternative scenarios. The higher cost per installed kWe and the uncertainty about alternative technologies for CO2 capture are among the key weak points of the technologies that were identified. Main results are summarised in Tables 1 - 3.

Tab. 1 Data on actual and future hard coal condensing steam power plants

Tab. 2 Data on future hard coal IGCC power plants

Tab. 3 Data on actual and future natural gas and steam power plants

For the subsequent analyses, two scenarios are taken into account: • a "Business as usual scenario" (BAU), where no specific constrain is assumed as regard CO2 emissions.

Some demonstrative projects may be implemented involving Carbon Capture and Storage" (CCS) technologies, but no political decision is taken enforcing or subsidising CCS deployment;

• a "Carbon Constrained scenario" (CC), where the CCS will progressively be deployed according to a political choice and targets at EU level.

In the BAU scenario, here chosen as Base Case, the considered technologies are:

For coal based generation - supercritical pulverised coal combustion plants; - integrated gassification combined cycle (IGCC) without CO2 capture.

For gas generation - gas turbine combined cycles (GTCC) of higher efficiency.

In the CC scenario, the considered technologies are:

For coal based generation - integrated gassification combined cycle (IGCC) with pre-combustion CO2 capture and

sequestration; - pulverised coal oxycombustion.

For natural gas generation

- CO2 capture is not considered convenient with GTCC, so no changes are expected in comparison to BAU scenario.

The choice of Baseline or “Reference technologies” is quite difficult because it is actually unknown if CO2 capture will became mandatory in the covered time period. Supposing mandatory the need to only reduce the CO2 emissions, the following technologies have been chosen as Base or reference: • Supercritical pulverised coal steam plants with efficiencies reaching 52 % for coal based power system; • Gas turbine combined cycles (GTCC) with efficiencies approaching 63 % for gas based power system. The technological options considered in this report for CC scenario are summarised as follows: • Option 1: Development of IGCC power systems for base-load applications; • Option 2: Development of a reliable and cost effective pulverised coal oxycombustion plant based on

evolution of actual technologies; Options 1 and 2 could be seen as technological alternatives; the choice between them is at present unpredictable and coexistence for some decades could be expected. The key problem in this case is cost reduction. Technological improvements in the next twenty years could bring these systems to an acceptable plant cost increase and lesser efficiency penalties. It is very difficult to predict which of the two alternatives will improve its performances in a more significant way, starting from an approximately balanced situation.

2.1.2 CO2 reduction only scenario (BAU) In the short to medium term, reductions in the greenhouse emissions of coal-fired power generation can be achieved by increased conversion efficiency. The efficiency of pulverised coal (PC) generation increased substantially at the end of the 20th century and, with the development of supercritical (SC) and ultra-supercritical (USC) processes, will continue its upward advance over the next two decades. Potential for improvements of SC-PC efficiency will be fully reached before 2025 CO2 capture, separation and geological storage technologies have been developed beyond the stage of technical feasibility. Research and industry are working at improving these technologies and demonstrate them in integrated configurations. Test/pilot plants are expected in early 2010’s; first commercial applications will be operational by 2025 and mature technology will be available before 2050. The efficiency of power plants using conventional high-temperature carbon steel alloys is restricted to values < 45%. Only at advantageous north-european cooling conditions efficiencies of 45% are reached. Siemens Power Generation states 44.5% as maximum efficiency for such hard coal power plants. Hard coal power plants with high efficiencies = 45% and power ratings > 300 MW require raising the live steam conditions on values exceeding 270 bar 580°C. Those steam conditions can be realised using ferritic-martensic materials (T 92, P 92, E 911 etc.), which facilitate to generate steam at high super-critical pressures and temperatures without austenitic materials. However they are about four times more costly than conventional ferritic alloys. These ferritic-martensic materials, have recently been developed in Japan (EP). In new modern power plants all these measures for efficiency enhancement are applied. Under the assumption that the efficiency of power plant processes components and boiler as they are applied in the ultra-supercritical power plant can’t be substantially improved, for efficiency improvement there is only the possibility to increase the steam temperature. It can be evaluated that an increase from 700°C to 800°C will improve the overall efficiency by 2.8 percent points. Starting from current condition, with this estimation, the highest efficiency attainable for hard coal condensing steam power plants is 55%.

Summarising it can be stated: • by the time horizon new hard coal power plants with efficiencies of 46 ÷ 48% can be realised; • in the period between 2015 and 2025 hard coal condensing steam power plants with efficiencies around

50% (maybe up to 52%) could be built; • between 2025 and 2035 it is assumed that new hard coal steam condensing power plants will be able to

reach efficiencies higher than 52%. Combined cycles gas turbine feature the best efficiency of all thermal based electricity generation technologies applied at present. The efficiency is mainly determined by the efficiency of the gas turbine generation. About two thirds of the capacity of the GTCC plant account for the GT, the remaining third is supplied by the steam turbine. The efficiency of the first is basically function on both the gas turbine inlet temperature (TIT) and the pressure ratio. Manufactures of heavy-duty gas turbines state an efficiency of 57.5% for current gas fired GTCC plants. The 60 % barrier is expected to be reached in a few years. The specific investment is anticipated to further decline as gas turbines with higher capacity are expected to penetrate the market. The technical development aims at the construction of gas turbines with a capacity of 500 MW but cost information on such future GT are not yet available from manufactures. As the specific investment costs of GTCC plants is approximately half of those of hard coal power plants, the fuel costs have considerable influence on their cost effectiveness. Summarising it can be stated: • between 2015 and 2025 it is anticipated that natural gas and steam power plants with capacities around

500 MW and efficiencies of 60% will be offered at the world market; • energy costs of these plants are calculated taking into account fuel savings due to higher efficiencies and

cost reduction due to higher capacities; • for 2025 to 2035 further efficiency enhancement at same capacity level is assumed. This implies gas

turbines with higher inlet temperatures (TIT > 1500°C with higher compressor pressure ratio) and advanced vane materials as well as enhanced vane cooling.

In the long run the efficiency of natural gas and steam power plants won’t exceed the 65% barrier, even if gas turbines with sequential combustion and measures for component enhancements are assumed.

2.1.3 Coal gasification As already seen, efficiencies higher than 55% are hardly achievable for conventional coal plants, even if applying Ni-based alloys. Thus other coal conversion technologies featuring higher efficiencies are needed. As cheapest and promising solution the combination of gas-fired gas turbines with downstream steam turbine turned out. As gas turbines however cannot be charged with un-cleaned flue gas from hard coal combustion, coal has to be gasified and transformed in a mixture of hydrogen and CO. This technology is known as IGCC (or integrated gasification combined cycle). IGCC power plants can be built using components and materials already approved and available in the market. Depending on the development of gas turbines, IGCC power plants can potentially feature higher efficiencies than steam power plants. If GTCC efficiencies will achieve 63% in future, hard coal IGCC plants could reach an efficiency around 56%. Summarising it can be stated: • by 2015 we can considers coal IGCC power plants as demonstration plants; • the actual most representative European IGCC power plants (Buggenum and Puertollano) are neither

representative in terms of costs nor in terms of efficiency;

• from 2015 to 2025 the technical data of the representative IGCC power plant stem from an IGCC optimisation in the EU funded study. Such a power plant could be built with current available and approved material, components and gas cleaning procedures. The efficiency of this power plant was calculated to 51.5% and can be achieved with gas turbine improvements which are anticipated by 2015; about 1100 US$/kW were calculated as specific investment costs;

• between 2025 and 2035 the efficiency is calculated according to the expected efficiency development of GTCC to 63 % - 8 % = 55 %. The efficiency reduction lies in the losses of gasification and gas cleaning. Postulated future progress in gasification and gas cleaning will reduce efficiency difference between IGCC and GTCC power plants.

2.1.4 CO2 capture scenario It is unlikely that any technology combination that includes CO2 capture and storage will be cost competitive with conventional coal-based PF generation, basically because of the additional energy requirements at the power plant, which cause substantial efficiency loss and need additional infrastructure. While costs should eventually fall significantly, there is considerable uncertainty about the impact on generation costs. There are several projects under way aiming at cost reduction of CO2 capture and storage (CCS). For example, the FutureGen project aims at producing electricity from a coal-fired power station incorporating carbon capture and storage at no more than 10% higher cost than one without CCS. However, this limited cost increase seems referring more to future commercial units than pilot plants starting operation in the next decades. Capture of CO2 can be achieved by separation either from the flue gas produced in conventional combustion or from the fuel gas before its combustion in gas turbines. Based on these two basic principles there are three main generic approaches for capturing CO2 from power plants: • Post-combustion capture; • Pre-combustion capture; • Oxyfuel combustion. Post-combustion capture involves the separation of CO2 from the flue gas. Flue gas separation and capture methods include several alternatives technologies like: chemical or physical absorption, solid adsorption/desorption, cryogenic separation and membrane separation. The preferred technique for post-combustion capture is at present the flue gas scrubbing with a chemical solvent followed by heat solvent regeneration to release high purity CO2. The most common solvents used in chemical absorption systems are alkanolamines such as MEA, DEA, and MDEA, but further developments are in progress. Pre-combustion capture involves reacting fuel with oxygen, and in some cases steam, to produce a gas consisting mainly of hydrogen and carbon monoxide (syngas). In a following shift reaction the latter is reacted with steam in a catalytic converter (shift reactor) to further hydrogen and carbon dioxide. Finally the carbon dioxide is separated and the hydrogen can be burned in a gas turbine (or used in fuel cells stacks). The advantage of pre-combustion capture relative to post-combustion capture is that a smaller volume of gas, richer in CO2 has to be treated. This reduces the size of the gas separation plant and thus reduces capital costs. Furthermore the higher concentration of CO2 enables less selective gas separation techniques to be used (e.g. physical instead of chemical solvents, adsorption/desorption). These require using less energy per unit mass of CO2 separated. Most of the technologies for pre-combustion capture are well proven in ammonia plants. However, the combustion system has to be completely redesigned and modified, thus costs and new risks arise. The oxyfuel combustion CO2 capture technology is based on the production of a highly concentrated CO2 stream directly in the combustion chamber, so that CO2 can directly be captured. Oxyfuel combustion involves burning fuel in an oxygen environment instead of ambient air. However, because the combustion temperature with pure oxygen would be too high, in order to control the combustion temperature, the oxygen is mixed with CO2 recycled from the exhaust. The needed oxygen is produced by an air separation unit (ASU).

As further result, the boiler thermal efficiency can be increased because the volume of inert gas in exhaust is reduced. The highly enriched CO2 flue gas stream enables simple and low cost CO2 purification methods to be used. The major drawback of this approach is that the production of O2 using conventional cryogenic air separation plants is expensive, both in terms of capital cost and energy consumption. Oxyfuel combustion technique can in principle be applied to conventional boilers and gas turbines too, although a different design of gas turbine would be needed to work with highly concentrated CO2, which rules out retrofitting to existing Gas Turbine Combined Cycle (GTCC) plants.

2.2 Optinon :1 IGCC Plants The basic engineering for a coal IGCC power plants with CO2 capture has already been investigated in an EC funded studies too, where costs of the power plant components for CO2 capture and compression were estimated. Meanwhile the energy demand for CO2 capture were also analysed: the CO2 capture caused an efficiency reduction of more than 6 % points compared to an IGCC power plant without CO2 capture. Next table shows data on IGCC power plants with CO2 capture obtained from engineering studies on IGCC CO2 capture using the Rectisol scrubbing process for CO2 separation. Summarising it can be stated: • in the time span by 2015 there is no representative coal IGCC power plant with CO2 capture considered

as there is no market introduction of IGCC, but only demonstration plants, which are planned without CO2 capture;

• between 2015 and 2025 as well as between 2025 and 2035 the costs and efficiency of the coal IGCC with CO2 capture are derived from hard coal IGCC without CO2 capture;

• the following reported data are calculated for a CO2 capture rate of 90%; • the CO2 abatement, compression and liquefaction costs account for 30 to 40 �/t CO2; pipeline

transportation cause additional costs approximately calculated (on the base of costs of actual technologies) to about 25 � /ton of liquefied CO2 transported in pipeline over long distances.

In the Report Rs1a it is not considered the promising technology of oxycombustion.

2.3 Option 2: PC oxycomb. For PC, two principal approaches can be implemented for CO2 capture: • separation from the flue gas at the back end of an otherwise largely conventional PC unit; • separation from the CO2-rich flue gas from oxy-combustion. With oxy-combustion, total thermal efficiency could be higher than with post-combustion scrubbing but obviously still lower than for conventional PC without CO2 recovery.

Data on future hard coal IGCC power plants with CO2 capture

Data on coal oxycombustion power plants with CO2 capture

Actual 2050 Gross Power MWe 773 773 Net Power MWe 553 670 Load h/year 7500 7500 Total Plant cost* $/kW 2900 2800 Efficiency decrease by CO2 capture points % 12 6 Net efficiency % 33.0 45.0

* in a NETL/DOE study the additional investment cost is estimated 1300 $/kW referred to net power

The following sections describe the alternative technological options mentioned above, as well as the main highlights that have come out from their comparison with the reference technologies on the basis of the set of criteria and indicators put forth by the D3.1 - RS 2b Report “Environmental, economic and social criteria and indicators for sustainability assessment of energy technologies”. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

��No or limited influence

� Small increase (less than 30%)

��Small decrease (less than 30%)

��Increase (about 50%)

� Decrease (about 50%)

2.4 Conclusions: resume tables

CRITERION INDICATOR UNIT IGCC PC oxycomb.

IGCC PC oxycomb.

1 ENVIRONMENT 1.1 RESOURCES 1.1.1 Energy Resources 1.1.1.1 Fossil primary energy Total consumption of fossil

resources (LCIA) MJ/kWh

�� lower efficiency lower efficiency

1.1.1.2 Other non-renewable energy Total consumption of uranium (LCIA)

MJ/kWh

1.1.2 Mineral Resources (Ores) Weighted total consumption of metallic ores (LCIA)

kg(Sb-eq.)/kWh � � Complex systems Small influence

1.2 CLIMATE CHANGE 1.2.1 Global warming potential (LCIA) kg(CO2-eq.)/kWh

�� CO2 capture

CO2 capture

1.3 IMPACT ON ECOSYSTEMS

1.3.1 Impacts from Normal Operation 1.3.1.1 Biodiversity (land use) Impacts of land use on ecosystems

(LCIA) PDF*m2*a/kWh � � no influence no influence

1.3.1.2 Ecotoxicity Impacts of toxic substances on ecosystems (LCIA)

PDF*m2*a/kWh � � Lower emissions Quite same emissions

1.3.1.3 Acidification and eutrophication Impacts of air pollution on ecosystems (LCIA)

PDF*m2*a/kWh � � Lower emissions Lower emissions

1.3.2 Impacts from Severe Accidents 1.3.2.1 Release of hydrocarbons Large release of hydrocarbons

(RA) t/kWh � � small influence small influence

1.3.2.2 Land contamination Catastrophic land contamination (RA)

km2/kWh � � no influence no influence


IGCC PC oxycomb.

1.4 WASTES

1.4.1 Special Chemical Wastes stored in Underground Depositories

Total weight of special chemical wastes stored in underground depositories (LCA)

kg/kWh � � no influence no influence

2 ECONOMY

2.1 IMPACTS ON CUSTOMERS

2.1.1 Price of electricity Average generation cost �/MWh �� lower efficiency

higher investments lower efficiency higher investments

2.2 IMPACTS ON OVERALL ECONOMY

2.2.1 Employment Direct jobs Person-years/GWh � � no influence no influence

2.2.2 Autonomy of electricity generation Medium to long term independence from foreign imports, based on domestic energy storage and/or resources

Ordinal � � possible use of domestic alternative fuels

no influence

2.3 IMPACTS ON UTILITY

2.3.1 Financial Risks

2.3.1.1 Capital investment exposure Total capital cost � � � more expensive technology

more expensive technology

2.3.1.2 Impact of fuel price changes Sensitivity to fuel price changes Factor � � Limited influence Limited influence

2.3.1.3 Risk due to changes in boundary conditions

Construction time Years � � Complex units Complex units

2.3.2 Operation


IGCC PC oxycomb.

2.3.2.1 “Merit order” for dispatch purposes Total average variable cost or “dispatch cost”

�cents/kWh � � lower costs with respect to low

larger units only

2.3.2.2 Flexibility of dispatch Composite indicator Ordinal � � longer start up and transient time

longer start up time

2.3.2.3 Availability Equivalent Availability Factor Factor � � lower availability expected for complex technology

Limited influence

3 SOCIAL ASPECTS

3.1 SECURITY/RELIABILITY OF ENERGY PROVISION

3.1.1 Political Threats to Continuity of Energy Service

3.1.1.1 Diversity of primary energy suppliers

Market concentration in the supply of primary sources of energy

Ordinal scale � � no influence no influence

3.1.1.2 Waste management Probability that waste storage facilities will not be available

Ordinal scale � � Small influence no influence

3.1.2 Flexibility and Adaptation Ability to incorporate new technological developments and breakthroughs

Ordinal scale � � Good influence for TG and O2 production

Good influence for O2 production

3.2 POLITICAL STABILITY AND LEGITIMACY

3.2.1 Potential of Conflicts induced by Energy Systems.

Potential of energy system induced conflicts that may endanger the cohesion of societies


3.2.2 Willingness to act (Mobilisation Potential)

Willingness of NGOs and other citizen movements to act for or against realisation of an option

Ordinal scale � �� no influence no influence


IGCC PC oxycomb.

3.2.3 Reliance on participate Decision-making Processes

Reliance on participate decision-making processes for different kinds of technologies


3.2.4 Citizen Acceptance of the System Empirical survey results on average citizen acceptance of specific energy technology

Ordinal scale � � no influence small influence

3.3 SOCIAL AND INDIVIDUAL RISKS

3.3.1 Expert-based Risk Estimates for Normal Operation

3.3.1.1 Reduced life expectancy due to normal operation

Mortality due to normal operation (EIA+LCA)

YOLL/kWh � � no influence no influence

3.3.1.2 Non-fatal illnesses due to normal operation

Morbidity due to normal operation (EIA+LCA)

DALY/kWh � � no influence no influence

3.3.2 Expert-based Risk Estimates for accidents

3.3.2.1 Expected Health effects from accidents

Expected Mortality due to severe accidents (RA)

Fatalities/kWh � � no influence no influence

3.3.2.2 Maximum consequences of accidents

Maximum credible number of fatalities per accident

Fatalities/accident � � no influence no influence

3.3.3 Perceived Risks

3.3.3.1 Perceived risk characteristics for normal operation

Subjectively expected health consequences of normal operation

Ordinal scale � � no influence small influence

3.3.3.2 Perceived risk characteristics for accidents

Psychometric variables such as personal control, catastrophic potential, perceived equity, familiarity


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Quite same fuels and residual to be transported

3 Fuel cells Mauro Scagliotti, CESI RICERCA, SSG Department

3.1 Technologies credited in RS1a for 2030 – 2050: brief description. Fuel cells are electrochemical devices that convert the chemical energy of a fuel and an oxidant to electrical energy (DC power), heat and reaction products. The fuel and oxidant are typically stored outside of the fuel cell, and transferred into the fuel cell as they are consumed. Different types of fuel cells exist depending on the electrolyte. The electrolyte choice determines the useful operating temperature range and therefore possible application. In order to achieve a useful voltage output, single cells have to be connected in series, in an assembly of that is named a fuel cell stack, including cells, separators, cooling plates, manifolds and supporting structures. One or more stacks, together with piping for conveying fuels, oxidant, exhausts and eventually additional fluids (e.g. cooling media), electrical connections and means for monitoring and/or control are parts of the so called fuel cell module. The fuel cell module is the main component of the fuel cell power system. The fuel cell power system comprises all the subsystems that are needed to fed the fuel cell with fuel and oxidant (fuel and oxidant processing systems), to manage the whole system and to produce useful electrical, and eventually thermal, power output(s). Fuel cell system configuration basically depends on the specific applications. Because of their scalability, fuel cells are presently under investigation for many different applications: micro power systems for electronic devices, portable systems for military and civil uses, power trains for vehicles, small back up power systems, large stationary power systems for base-load generation and so on. According to NEEDS project purposes, only some stationary application will be addressed herein and namely stationary systems for power generation in residential and industrial environments. Stationary applications have less stringent requirements in terms of power density, weight and start up fastness with respect to other applications, such as automotive applications. In principle, all the fuel cell technologies could be used for stationary applications, including AFC (Alkaline Fuel Cells), DMFC (Direct Methanol Fuel Cells), PEFC (Polymer Electrolyte Fuel Cells), PAFC (Phosphoric Acid Fuel Cells), MCFC (Molten Carbonate Fuel Cells) and SOFC (Solid Oxide Fuel Cells). High temperature SOFCs and MCFCs, in particular, appear suitable in view of a transition to the hydrogen economy and they should be always taken into account in long term scenarios. They can operate on today’s commercially available hydrocarbon fuels with significant efficiency gains, on renewable biofuels, when these will become cost effective, and ultimately on hydrogen, when it will become widely available. Most of the fuel cell technologies for stationary applications are presently in a proto-commercial phase. Small stationary fuel cell power systems (< 10 kWe output) are mostly based on PEFC and to less extent to SOFC, whereas within large stationary fuel cell power systems (>10 kWe) hundred kWe or MW class MCFC and PAFC systems were installed and operated, as well as PEFC and SOFC systems with power output around some tenths – one hundred kWe class. Extensive field tests and demonstration programmes are currently ongoing in United States, Japan and Europe on small and large fuel cell power systems for stationary applications. Field tests in real world conditions allow gaining experience on fuel cell long term behaviour in environment and load conditions that may be very different with respect to a well controlled laboratory set up. They are contributing to the build up of operational databases and to more reliable technology assessments. Combining field test experiences with targeted R&D actions seems to be the right strategy to further develop fuel cell technologies and fill the gap with competing technologies. Fuel cell technologies are in general not yet mature for market entry. Only in few niche markets, such as back up power and emergency generators, they appear already technically and economically viable with respect to conventional technologies. The high cost per installed kWe, the limited durability and the presence of many valid competitors are among the key weak points of the present fuel cell technologies that were identified in RS 1a Final Report on Fuel Cells (D9.2 - RS 1a “Final report on technical data, costs and life cycle inventories of fuel cells”). The authors of the RS 1a Final Report on Fuel Cells adopt a “learning curves” approach to analyse possible future developments in terms of cost reduction and lifetime improvements and refer to ESTEC scenarios

performed in IEA for global stationary fuel cell future use. Results are summarised in table 1. Unfortunately fuel cell technologies are at an early stage of development and the degree of uncertainty on cost reduction is extremely high. A pessimistic scenario in which no evolution neither affirmation of fuel cell technologies take place has also to be considered. In the optimistic - realistic (RO) scenario it was assumed that the technology development stage will last for the entire time horizon of the study. In the very optimistic scenario a wider use of fuel cells is considered with 10 GW installed in 2025 and 320 GW installed in 2050. Other views, however, are available in literature. For example the European roadmap for the development and deployment of hydrogen and fuel cell technologies (“European Hydrogen and Fuel cell Platform, 2005: www.hfpeurope.org/hfp/keydocs) has set a target of about 1 GW of distributed power generation capacity in Europe from fuel cells by 2015.

table 1 Global fuel cell capacity (GW) installed in 2005, 2025 and 2050 under different technology development scenarios (from IEA sources) Global fuel cell installed capacity Scenarios (Year) 2005 2025 2050 Pessimistic (GW) 0.1 0.1 0.1 Optimistic-realistic (GW) 0.1 0.5 200 Very optimistic (GW) 0.1 10 320 The perspective as of 2025 and 2050 of only three fuel cell technologies, namely PEFC, MCFC and SOFC, were made out in RS 1a Final Report on Fuel Cells from three different scenarios of worldwide deployment of fuel cell power systems over the same period. The authors did not considered the presently most mature fuel cell technology, PAFC technology, due to the lack of Life Cycle Assessment (LCA) data and because PAFC technology was not included among the most promising fuel cell technologies for stationary applications in OECD 2005 – Prospects for hydrogen and Fuel Cells, IEA Study, Paris, France. In the RS 1a Final Report on Fuel Cells the following have been chosen as reference technologies:

• Small SOFC stationary fuel cell power system, 1 kWe output • Large CHP SOFC stationary fuel cell power system, 250 kWe output • Small PEFC stationary fuel cell power system, 2 kWe output • Large MCFC stationary fuel cell power system, 250 kWe output

The choice of “reference technologies” at the present stage of development is very difficult and it is likely to have little sense. As far as stationary applications are considered, neither “winning” nor “most promising” fuel cell technologies can be defined now. The competition among all the fuel cell technologies is still open. In particular, fuel cell technologies that have lost their popularity, such as PAFC and AFC, are not ruled out from this competition: in 2009, for example, UTC (PAFC) will launch its 400kW PureCell unit at the forward pricing of 2500 $/kWe installed, while AFC Energy has a deal with Akzo Nobel to ship a 50 and a 200 kWe AFC unit, contingent on further development. The list of fuel cell developers is fluid. Business targets are frequently changed due to the alternating of promising results and failures. Important events occurred during the period covered by the NEEDS project. Ballard abandoned some years ago the field of PEFC large stationary applications and focused only on automotive, small back up and small residential (1 kWe) application. More recently, in June 2008, Siemens announced that the fuel cell business “is not a core competency for its energy business” and after many years of basic research and product development it is looking to sell its SOFC business (about 130 employees in Pittsburgh). SOFC Siemens-Westinghouse technology was unanimously considered as one of the most reliable fuel cell technologies, with impressive endurance records at laboratory and system level, but with very high costs. Other SOFC developers, such as Rolls Royce, have still to demonstrate similar technical results. The practical feasibility of large SOFC power systems, eventually coupled with a gas turbine in hybrid configuration, is uncertain with the presently available technologies. Large CHP SOFC stationary fuel cell power systems, 250 kWe output, should be therefore moved from the reference technology list to the alternative future options. Thanks to the progresses achieved by Fuel Cell Energy and CFC Solutions, it appears more reasonable to consider only a 250 kWe class MCFC system as a reference for large stationary applications.

The technological options considered in this report can be summarised as follows: • Baseline technologies: As baseline technologies, PEFC and SOFC technologies are considered for small

residential CHP applications, whereas only MCFC technology is considered for large, 250 kWe output, CHP applications for the reasons explained here above.

• Option 1: Development of a reliable and cost effective fuel cell technology based on solid polymers and operating around 150 °C for small residential applications.

• Option 2: Development of larger, multi-MW class MCFC power systems for base-load applications • Option 3: Development of a reliable and cost effective SOFC technology suitable to be scaled up at

multi-MW size hybrid power systems. Alternative options 1 and 2 could be seen as technology gaps. High temperature PEFC (HT-PEFC) operating above 100 °C are presently under development and some promising results have been achieved at laboratory level. MCFC have already demonstrated interesting targets. The key problems in this case are cost reduction and durability. Technological improvements in the next twenty years could bring MCFC systems to an acceptable cost and in this case it could be interesting to consider larger power system sizes, eventually coupled with a gas turbine, with higher efficiency. The present choice of developing 250 kWe units was strongly influenced by the lesson learned on PAFC technology. The multi-MW option is unsuitable at the stage of field tests on proto-commercial power systems due to the extremely high capital costs of prototypes that strongly limit the number of tested systems and test sites. A more mature and cost effective MCFC technology should not be limited to hundred kWe power systems size, as modelling studies demonstrated that this technology is in principle suitable for the realization of hybrid systems of some tenths of MW with electrical efficiencies approaching 70%. Option 3, if feasible, would turn out as real technological breakthroughs. As a matter of fact, despite many interesting results achieved in the last twenty years by different manufacturers, solid oxide fuel cell power systems are available only with power outputs of some tenths kWe. The following sections describe each of the alternative technological options mentioned above, as well as the main highlights that have come out from their comparison with the reference technologies on the basis of the set of criteria and indicators put forth by the D3.1 - RS 2b Report “Environmental, economic and social criteria and indicators for sustainability assessment of energy technologies”. Lastly, a full overview of the results of these comparisons and the reasons underlying them, is appended at the end of this chapter. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

No influence

Increase (about 50%) Small increase (less than 30%) Small decrease (less than 30%)

Decrease (about 50%)

3.2 Option 1: High temperature PEFC

3.2.1 Technologies gap description PEFC have been considered as baseline technology, together with SOFC, for small residential CHP applications (about 2 kWe). As a matter of fact, PEFC is one of the most promising energy technology into a hydrogen economy scenario and stationary applications could also benefit of the massive investments for the development of fuel cell power trains into the automotive market. At present, however, only hydrocarbon fuels are commercially and widely available: the transition to a hydrogen economy will require several decades. PEFC systems for small residential applications (figure 1) should be therefore fuelled in the next

future with natural gas, LPG or other available hydrocarbon fuels in order to benefit of the already existing infrastructures. Unfortunately, PEFC operating below 100 °C have to be fed with pure hydrogen. This increases the complexity (fuel processing subsystem), and consequently the cost, of small power systems. With this in mind it would seem reasonable to take into account an option where small stationary power systems would be based on PEFC that can operate around 150 °C (HT-PEFC). HT-PEFCs have demonstrated at laboratory level a high tolerance to carbon monoxide and to other species that are present in hydrocarbon fuel reformates. As a consequence, the fuel processing subsystem is expected to be simpler with respect to the low temperature PEFC option. As a main drawback, high temperature PEFCs based systems have a longer cold start up time and a lower flexibility of dispatch. This lack of flexibility could be overcome, however, by connecting several power systems with a unique control system into a ”virtual power system” and by operating only a proper number of small power systems following the load demand.

figure 1 A few examples of 1 kWe class PEFC power systems installed in Japan within the large – scale stationary fuel cell demonstration project (from T. Omata, Proc. 2007 Fuel Cell Seminar, San Antonio, Texas, USA, Abstract N. 63)

3.2.2 Technologies gap influences on criteria Environment. Hydrogen is presently produced mainly from fossil sources (natural gas) through a steam reforming process. Cost effective technologies to produce this energy vector from renewable sources (for example through water electrolysis by using solar energy) are not available now. The strict requirements on hydrogen purity make therefore low temperature PEFC unsuitable in a transition phase to hydrogen economy. More efficient fuel cell technologies should be preferred for stationary applications if fossil fuels are used. High temperature PEFC, having less strict requirements on hydrogen purity, would allow a more extensive use of biofuels also in small power systems, with positive impact on the environment. Economy. The main features of the HT-PEFC option that may impact on economic indicators are the electric efficiency and the fuel purity. Efficiency is expected to be higher with respect to low temperature PEFC and the impact on operation costs should be positive. The requirements on fuel purity would be less strict with respect to low temperature PEFC baseline option, allowing for example a more extensive use of biofuels as raw fuels, with positive impact also on autonomy of electricity generation (use of domestic renewable energy resources). On the other hand the operational flexibility would be worse with respect to baseline technology with a slightly negative impact on economic indicators such as flexibility of dispatch.

Social Aspects. The high temperature PEFC option is expected to be neutral as far as social indicators are considered with respect to low temperature PEFC, including risk estimates, visual impact, noise, grid interfacing.

3.3 Option 2: Larger MCFC power systems

3.3.1 Technologies gap description MCFC have been considered as baseline technology, together with SOFC, for large CHP applications (about 250 kWe) in RS 1a Final Report on Fuel Cells. The very slow development tracks and recent events make the hypothesis of large SOFC systems rather unrealistic at present. This technology was therefore maintained only in the small residential application baseline technologies. Only MCFC is considered as baseline technology for large, 250 kWe output, CHP systems. Extensive field tests are ongoing on units of this size from leading manufacturers. The results are promising, the costs are decreasing and the electrochemical module durability is increasing. Further incremental improvements are expected to lead durability and costs to a market acceptable level, as several targeted R&D actions are ongoing on these issues. At the present stage of development the manufacturers are focused on units with a few hundred kWe output for practical reasons, including reasonable capital costs for the early users, but in several cases two or more units (figure 2) are installed together at the same site to satisfy the thermal and electric load demand. With this in mind it would seem reasonable to take into account an option of larger (MW or multi-MW class) and more efficient MCFC units, eventually coupled with a gas turbine in hybrid systems.

figure 2 Four MCFC units from Fuel Cell Energy (DFC®300 model) installed on the roof of the Sheraton Hotel in San Diego. Following FCE specifications DFC®300 model can supply up to 300 kWe at a rated efficiency of 47% (Source: Fuel Cell Energy).

3.3.2 Technologies gap influences on criteria Environment. Multi-MW class MCFC power systems are more efficient with respect to competing technologies for distributed power generation, such as gas engines, microturbines, etc with the same rated power output, and could be also more efficient with respect to smaller 250 kWe MCFC power systems (baseline technology), as they can be effectively coupled with gas turbine in hybrid systems. Therefore if one assumes to install the same overall capacity, the consumption of primary energy from fossil fuels or from renewable biofuels would be lower, with a positive impact on the ecosystem with respect to the baseline technology. The higher

efficiency of MW class MCFC option would positively impact also on the global warming potential indicator when fossil fuels are used as a source. As far as raw materials are considered, larger MCFC power systems would allow materials to be saved in the balance of plant construction (stainless steel), whereas the amount of the materials used for the electrochemical module fabrication (nickel, stainless steels, ceramic and alkali carbonates) should be independent on the power system size. All these materials, however, could be in principle recovered at the end of life of the power system, making the larger MCFC option neutral from an environmental viewpoint.

figure 3Fuel Cell Energy 1 MW class MCFC model DFC®1500 installed at the wastewater treatment plant of King County and operated with gas from an anaerobic digester. Following FCE specifications DFC®1500 model can supply up to 1.4 MWe at a rated efficiency of 47% (Source: Fuel Cell Energy).

Economy. Since larger units are more efficient with respect to the baseline 250 kWe MCFC technology, the average electric power generation cost is expected to decrease. The impact on the employment would be slightly negative, as for a fixed overall installed capacity fewer power systems would result in a lower amount of labour required to build, operate, maintain and decommission the power systems. MCFCs appear suitable to use domestic renewable biofuels independently on their rated power output and fuel flexibility in operation from natural gas to biogas and viceversa was already demonstrated making the multi – MW option more or less neutral as far as autonomy of electricity generation is considered. The total capital cost of the multi MW option is of course higher with respect to the baseline 250 kWe option. The impact on the utility (or owner) financial risks would be slightly negative. MCFC technology is presently suitable only for baseload generation, independently on the power system size. The flexibility of dispatch is null in any case. On the contrary on a mature MCFC technology a high availability factor is expected. Past and present experiences are showing that most of the failures that are responsible of MCFC power system unscheduled shut downs occur outside the electrochemical module. From a statistic viewpoint the multi MW option is therefore expect to have a slightly positive impact also on the availability factor with respect to the baseline for a fixed overall installed capacity. Social Aspects. The increase in MCFC power system size with respect to the baseline option is not expected to have significant impact on social criteria and indicators as far as security of energy provision, political stability, social and individual risks are considered. Larger MCFC units would produce more or less the same level of noise, whereas only the aesthetic impact would be worse. The multi MW MCFC option would be neutral or would have only a slightly negative impact as far as social acceptance and effects on the quality of landscape and residential area are considered.

3.4 Option 3: Innovative SOFC

3.4.1 Revolutionary Technologies break-throughs description As previously discussed, SOFC technologies have been widely investigated in the last decades. Different functional materials, cell design and manufacturing technologies have been tested. Innovative components in particular have been set up allowing SOFC to operate at intermediate temperatures (around 750°C). Despite of such a big R&D effort, however, excellent results were achieved only at laboratory level and on small (a few kWe) power system. Only one large power system, 100 kWe output, was successfully demonstrated for a few tenth thousands hours. The development of larger systems and in particular of hybrid systems (SOFC coupled with gas turbine) was announced by different manufacturers, but field tests on prototypes are continuously postponed. The actual development of large SOFC prototypes is facing great difficulties. At the present development level the SOFC scalability to large power system of some hundred kWe is doubtful and a technological break-through is needed. Therefore a SOFC technology for large stationary applications will be taken into account herein as revolutionary technology. It should be pointed out that the solid oxide technology that will be considered in this section will be different from that operating between 900 and 1000°C and based on zirconia electrolytes. A SOFC technology operating between 600 and 800°C should be more suitable to be scaled up at reasonable costs. Lower operating temperatures should result in the use of less expensive materials.

3.4.2 Technologies break-throughs influences on criteria Environment. High temperature fuel cell technologies exhibit higher electrical efficiency with respect to competing technology for stationary application having the same rated power and the requirements on fuel purity are less strict with respect to low temperature fuel cell technologies. As far as energy resources are considered the diffusion of efficient technologies for distributed power generation would result in a lower consumption of fossil fuels to produce the same amount of electric energy, with a positive impact also in global warming potential indicator. High temperature fuel cells such as SOFC do not need precious metal catalysts and rare metals, and do not impact on mineral resources indicators. During normal operation SOFC power systems, like other fuel cell technologies, have extremely low emissions with negligible impact on the surrounding environment. Pollutants are emitted mainly in the processing of metal ores that are used as raw materials. From this viewpoint the present SOFC technology is not worse than other high temperature fuel cell technologies, such as MCFC. The technological breakthroughs, however, are expected on cell components materials and fabrication processes. Therefore is not possible now to completely evaluate the possible impact on pollutant emissions during the whole life cycle of an innovative SOFC technology. Economy. The electricity generation cost at the busbar would be lowered in case of diffusion of highly efficient SOFC power systems. SOFC power systems can be in principle operated with a variety of raw fuels. Natural gas is the main choice at present, but also coal gas or biofuels could be used, thus improving the long term independency from foreign energy sources. Innovative SOFC, eventually coupled with gas turbine in efficient hybrid power systems, are expected to have a very limited flexibility as far as load following and should be used mainly for base load generation. A mature SOFC technology is expected to reach very high reliability and availability figures. Social Aspects. At least at the present level of development, fuel cell technologies, and SOFC in particular, are very sophisticated, thus requiring skilful and well trained worker in the technology chain. The diffusion of a new cost effective SOFC technology for large stationary applications should positively impact on “Work quality” indicator. Aesthetic impact on landscape would be the same of other fuel cell technologies of the same size. The same is true for noise impact. Noise emissions from fuel cell power systems are generated by compressors, blowers, pumps and other ancillary components that are required to supply (and remove) fluids to (from) the electrochemical module. The noise emission level may be influenced by the choice of operating the fuel cell at ambient or at higher pressure, or eventually by the power system size (amount of fluids to be supplied), but it is not expected to depend significantly on the fuel cell technology.

3.5 Conclusion: resume tables

CRITERION INDICATOR Direction of scale

UNIT High temperature PEFC

Larger MCFC power systems

Innovative SOFC

High temperature PEFC


Innovative SOFC

1 ENVIRONMENT 1.1 RESOURCES 1.1.1 Energy Resources 1.1.1.1 Fossil primary energy Total

consumption of fossil resources (LCIA)

min MJ/kWh

�� higher efficiency

fewer manufactured.units and higher efficiency higher efficiency

1.1.1.2 Other non-renewable energy

Total consumption of uranium (LCIA)

min MJ/kWh

� � � � � �see above, no increase in fossil fuel use

see above, no increase in fossil fuel use



min kg(Sb-eq.)/kWh

� � � � � �same number of units, but simpler structure.

fewer manufactured units

unpredictable, as breakthrough could be related to new materials

1.2 CLIMATE CHANGE 1.2.1 Global

warming potential (LCIA)

min kg(CO2-eq.)/kWh

� � � � ��higher efficiency higher efficiency higher efficiency 1.3 IMPACT ON

ECOSYSTEMS

1.3.1 Impacts from Normal

Operation

1.3.1.1 Biodiversity (land use) Impacts of

land use on ecosystems (LCIA)

min PDF*m2*a/kWh

� � � � � �no influence

fewer and larger units; higher efficiency higher efficiency




Innovative SOFC



Innovative SOFC


min PDF*m2*a/kWh

�� no influence


1.3.1.3 Acidification and eutrophication

Impacts of air pollution on ecosystems (LCIA)

min PDF*m2*a/kWh

� � � � ��no influence


1.3.2 Impacts from Severe Accidents

1.3.2.1 Release of hydrocarbons Large release of hydrocarbons (RA)

min t/kWh

� � � � � �no influence no influence no influence 1.3.2.2 Land contamination Catastrophic

land contamination (RA)

min km2/kWh

� � � � ��no influence no influence no influence 1.4 WASTES

� � 1.4.1 Special Chemical Wastes

stored in Underground Depositories


min kg/kWh

�� no influence no influence no influence 1.4.2 Medium and High Level

Radioactive Wastes to be stored in Geological Repositories

Total amount of medium and high level radioactive wastes to be stored in

min m3/kWh

�� no influence no influence no influence




Innovative SOFC



Innovative SOFC

geological repositories (LCA)

2 ECONOMY � �


� �

2.1.1 Price of electricity Average generation cost

min �/MWh

�� higher efficiency higher efficiency higher efficiency 2.2 IMPACTS ON OVERALL

ECONOMY

� � 2.2.1 Employment Direct jobs max Person-

years/GWh

�� no influence no influence no influence 2.2.2 Autonomy of electricity

generation Medium to long term independence from foreign imports, based on domestic energy storage and/or resources

max Ordinal

�� possible use of domestic biofuels

use of coal gas and domestic biofuels

use of coal gas and domestic biofuels

2.3 IMPACTS ON UTILITY � �

2.3.1 Financial Risks � �




Innovative SOFC



Innovative SOFC

2.3.1.1 Capital investment exposure Total capital cost

min �

��

same number of units, but simpler structure. larger units

more expensive technology

2.3.1.2 Impact of fuel price changes Sensitivity to fuel price changes

min Factor

�� higher efficiency higher efficiency higher efficiency 2.3.1.3 Risk due to changes in

boundary conditions Construction time

min Years

�� no influence larger units no influence 2.3.2 Operation

� � 2.3.2.1 “Merit order” for dispatch

purposes Total average variable cost or “dispatch cost”

min �cents/kWh

��

lower dispatch costs with respect to low temperature PEFC

larger units only for baseload

units only for baseload

2.3.2.2 Flexibility of dispatch Composite indicator

max Ordinal

�� longer start up times

longer start up times

longer start up times

2.3.2.3 Availability Equivalent Availability Factor

max Factor

�� no influence

higher availability factor expected for mature technology

higher availability factor expected for mature technology

3 SOCIAL ASPECTS � �


� �


� �




Innovative SOFC



Innovative SOFC



min Ordinal scale

�� no influence no influence no influence 3.1.1.2 Waste management Probability

that waste storage facilities will not be available

min Ordinal scale

�� no influence no influence no influence 3.1.2 Flexibility and Adaptation Ability to

incorporate new technological developments and breakthroughs

max Ordinal scale

�� no influence no influence no influence 3.2 POLITICAL STABILITY

AND LEGITIMACY

� � 3.2.1 Potential of Conflicts

induced by Energy Systems. Potential of energy system induced conflicts that may endanger the cohesion of societies

min Ordinal scale

�� no influence no influence no influence 3.2.2 Willingness to act

(Mobilization Potential) Willingness of NGOs and other citizen movements to act for or against realisation of an option

Stakeholder dependent

Ordinal scale

�� no influence no influence no influence




Innovative SOFC



Innovative SOFC

3.2.3 Reliance on participative Decision-making Processes

Reliance on participative decision-making processes for different kinds of technologies


Ordinal scale

�� no influence no influence no influence 3.2.4 Citizen Acceptance of the

System Empirical survey results on average citizen acceptance of specific energy technology

max Ordinal scale

�� no influence no influence no influence 3.3 SOCIAL AND

INDIVIDUAL RISKS

� � 3.3.1 Expert-based Risk

Estimates for Normal Operation

� � 3.3.1.1 Reduced life expectancy

due to normal operation Mortality due to normal operation (EIA+LCA)

min YOLL/kWh

�� no influence no influence no influence 3.3.1.2 Non-fatal illnesses due to

normal operation Morbidity due to normal operation (EIA+LCA)

min DALY/kWh

�� no influence fewer and larger units no influence


min � �



min Fatalities/kWh





Innovative SOFC



Innovative SOFC



min Fatalities/accident

�� no influence no influence no influence 3.3.3 Perceived Risks

� � 3.3.3.1 Perceived risk

characteristics for normal operation


min Ordinal scale

�� no influence no influence no influence 3.3.3.2 Perceived risk

characteristics for accidents Psychometric variables such as personal control, catastrophic potential, perceived equity, familiarity

min Ordinal scale

�� no influence no influence no influence 3.3.4 Terrorist Threat

� � 3.3.4.1 Potential of attack Potential for a

successful attack (RA)

min Ordinal scale


3.3.4.2 Effect of a successful attack Likely potential effects of a successful attack (RA)

min Expected number of fatalities

�� unmanned normal operation

unmanned normal operation

unmanned normal operation




Innovative SOFC



Innovative SOFC

3.3.4.3 Proliferation Potential for misuse of technologies and substances within the energy chain

min Ordinal scale

�� no potentially dangerous substance

no potentially dangerous substance


3.4 QUALITY OF LIFE � �

3.4.1 Socially compatible development

� � 3.4.1.1 Equitable life conditions Share of the

effective electricity costs in a social welfare receiver budget

min %

�� higher efficiency and lower kWh costs

higher efficiency and lower kWh costs

higher efficiency and lower kWh costs

3.4.1.2 Work quality Weighted index of work qualifications

max Factor

�� no influence no influence need for some more special skills

3.4.2 Effects on the Quality of Landscape and Residential Area

� � 3.4.2.1 Effects on the quality of the

landscape Functional and aesthetical impact of energy infrastructure on landscape

min Ordinal scale

�� no influence

larger units have an higher impact on landscape no influence




Innovative SOFC



Innovative SOFC

3.4.2.2 Noise exposure Number of residents feeling highly affected by noise caused by the energy facility or transports to and from the energy facility

min Ordinal scale

�� same noise level

same noise at a more limited number of sites same noise level

3.4.2.3 Contribution to traffic Total traffic load (LCA mainly)

min to be determined

�� same units to be transported

power systems assembled on site

power systems assembled on site

35

4 Offshore Wind Technology

Claudio Casale, CESI RICERCA, SSG Department

4.1 Technology credited in RS1a for 2025-2050 The wind has been used as an energy source by mankind since the most ancient times, but the production of electricity by modern wind turbines started only in the early 1980’s as a possible way to replace conventional fuels, at least to some extent. Ever since, concerns about the environment, growing energy demand, fuels prices and political turmoil in key areas of the world have spurred the governments of many countries worldwide (particularly countries of Europe and North America, but also China, India etc.) to promote the deployment of wind power plants. The world’s overall capacity of wind power plants has been growing steadily at a striking pace, reaching 100 GW in early 2008. This capacity has been composed mainly of grid-connected clusters of several wind turbines (wind farms), mostly located on land, even though larger and larger plants have begun to be built offshore in Europe in the last decade. The technology of wind turbines, too, has been making continuous progress, putting on line increasingly large, reliable and cost-effective machines. The wind energy resources are in principle extremely large, but their exploitation is heavily limited by the actual availability of sites that hold all the technical and non-technical requisites for wind power plants (wind farms), not to mention the problems that often arise from the need to gain acceptance of these plants by the public. On the other hand, wind power plants offer strategic and environmental advantages. They have rather high construction costs per unit capacity installed (�/kW) as compared to conventional plants, but their operation and maintenance costs are pretty low, as the wind resource is free of charge. Moreover, after the phase of manufacturing and installing wind turbines, these plants give out no greenhouse gases or polluting emissions during their operating lifetime. Conversely, wind energy has setbacks such as its low concentration, which makes for very bulky machines as compared to their power output, and variability and poor predictability over time, which puts wind farms among those power plants (like e.g. run-of-river hydropower plants) which can provide only limited amounts of “firm” power to the electrical system. Neither can wind energy be stored, unless in small quantity or in cases of special system configurations (e.g. in combination with water reservoirs). Consequently, wind farms need the presence of other generating plants that can help keep the balance between supply and demand on the grid in order to uphold frequency and voltage. This fact actually sets an upper limit to the wind capacity that can be connected to a given grid, depending on its characteristics. Further limitations to wind farms come from environmental issues such as the involvement of large extents of land, the visual impact of large numbers of machines ever growing in size, the emission of noise, the possible e.m. interferences, and the disturbance or danger to wildlife, especially to birds. These issues and the likely forthcoming shortage of land sites, especially in Europe, have recently roused more and more interest in offshore sites as an alternative for installing a substantial share of the new wind capacity foreseen over the next few decades. Offshore sites have significantly higher wind speeds and more stable wind conditions, which make for remarkably higher energy production (3000-4000 equivalent hours/year at full capacity instead of 2000-2500) and longer life of wind turbines. Many environmental issues, such as the extent of involved surface, visual impact, noise and e.m. interference, look less binding at offshore sites. On the contrary, some other peculiar aspects, such as the disturbance to marine wildlife, fishery and sea traffic, may well come up in this case, but do not seem however so critical provided suitable sea areas are chosen. Today’s technology of offshore wind farms is feasible in waters deep up to 30 m, as wind turbines are fixed to the sea bottom through foundations of various designs (typically gravity or monopile foundations). As projects are moved to deeper areas, new kinds of fixed foundations will have to be used (tripod, jacket or improved gravity foundations) likely up to 60-100 m depth (the deepest waters so far reached are 45 m in depth), then floating wind turbines (yet to be demonstrated as technically and economically feasible) could be the only practicable solution. As to wind turbines, today’s offshore machines are basically developments of on-shore models fitted out for the marine environment. Typically, wind turbines for offshore plants are chosen among the largest sizes. Big unit size, along with available space, sets the conditions for installing pretty big capacities at each wind farm.

36

Actually, transportation and installation of large machines become easier at offshore sites than on land, especially if these machines are manufactured at seaside places. However, purposely-built craft (large barges with cranes and jack-up legs) are needed to carry the wind turbines and foundation elements to site, lay foundations and set up machines. The cost of offshore foundations and installation adds over 50% to the total plant cost as compared to land-based plants, but their higher electricity production could in principle make up for that, at least to some extent. Today’s offshore plants, existing or under construction, are all made up of horizontal-axis wind turbines, with three blades. Power regulation through blade pitch control and operation at variable rotor speed thanks to a static frequency converter have become common features to all large-sized models. Most wind turbines currently operating offshore have unit rated powers ranging from 2 to 3.6 MW and rotor diameters from 80 to 107 m. Also some units rated at 5 and 6 MW with rotor diameters up to 127 m have already been put in operation, and machines of this size are likely to be widely used for offshore applications in a short time. While wind turbine nacelles and their towers are made mostly of steel, blades are generally made of glass fibres, carbon fibres, wood, bonded by epoxy resin. In all likelihood, the technology is now very close to the upper size limit for current materials. As wind turbines grow further in capacity above 5-6 MW, new materials and new manufacturing methods will be required to reach such large dimensions, in order to keep the weight of components within acceptable limits for structural stresses and transportation, and have, at the same time, adequate strength against ever growing loads. Research on these challenging issues has already got under way, among others within the UpWind project funded by the European Union under the Sixth Framework Programme, but it is still too early to say whether and when any major breakthroughs can actually be envisaged. However, it seems that such technological developments are likely to occur only gradually over the years up to 2050. An attempt at figuring out this evolution in machine size for offshore installations, while keeping as basic reference technology the current horizontal-axis wind turbines, was made in NEEDS Project’s RS 1a Final Report on Offshore Wind Technology (Deliverable No. T 10.04 – RS 1a). Prospective wind turbine sizes as of 2025 and 2050 were made out in this report from three different scenarios of worldwide deployment of offshore wind farms over the same period. These scenarios showed different rates of growth (pessimistic, optimistic-realistic, and very optimistic development) and were, in turn, chosen among a number of scenarios shaped by the IEA (International Energy Agency), the EWEA (European Wind Energy Association), the GWEC (Global Wind Energy Council) and Greenpeace. A summary of the main features of the three scenarios adopted by the RS1a report is given in table 2below. As can be seen, the world’s offshore wind capacity should be 10% of total in 2025 and 20% of total in 2050. The same percentages might be considerably higher in Europe alone, where offshore plants are foreseen to play a major part in future wind farm deployment. table 2 – Growth of wind capacity and wind electricity production worldwide up to 2050 under the three scenarios assumed by the RS 1a Final Report on Offshore Wind Technology. Global wind capacity (GW) Global wind production

(TWh) Global offshore wind

capacity (GW) Scenarios 2005 2025 2050 2005 2025 2050 2005 2025 2050 Pessimistic 59 300 577 124 730 1517 0.7 30 115 Optimistic-realistic

59 850 1557 124 2070 4092 0.7 85 310

Very optimistic

59 1600 3010 124 3900 7911 0.7 160 600

Table 2 reports briefly some of the main technical and economic figures that characterize the growth in offshore wind turbine size as it was outlined by the RS 1a report from the scenarios of table 1Also water depth has been considered, as this parameter has an obvious influence on the technical characteristics and cost of undersea foundations. For the sake of simplicity, Table 2 only focuses on the size trend that was drawn from the optimistic-realistic scenario. On the other hand, this intermediate trend was also taken as reference by the RS 1a report for its own Life Cycle Inventory of offshore wind technology.

37

table 3 – Development trend of horizontal-axis wind turbines for offshore wind farms up to 2050, as figured out by the RS 1a Final Report on Offshore Wind Technology from its Optimistic-realistic Scenario. 2005 2025 2050 Rated wind turbine capacity (MW) 2 12 24 Hub height (m) 60 140 160 Rotor diameter (m) 80 160 250 Water depth (m) 10-30 20-60 >100 Specific investment cost of the whole plant (million �/MW)

1.8 1.1 1.0

In the analysis reported on in the following, the technology described in table 2has been taken as the baseline offshore wind technology for evaluating the sensitivity, from the viewpoint of sustainability performance, of alternative technological options that can be envisaged for offshore wind farms in the same time frame, with a view to the subsequent Multi-Criteria Decision Analysis (MCDA) that will have to be carried out in RS 2b of the NEEDS Project. For this purpose, the variations in sustainability performance of the other technological options in respect of the baseline technology have been assessed by applying the set of criteria and indicators defined in the RS 2b Report “Environmental, Economic and Social Criteria and Indicators for Sustainability Assessment of Energy Technologies” (Deliverable No. D 3.1 - RS 2b). The technological options considered in this report can be summarised as follows: • Baseline technology: horizontal-axis wind turbines rated at 12 MW in 2025 and 24 MW in 2050, on

foundations laid on the sea bottom up to 100 m of water depth (it has been assumed here that technical progress can make fixed foundations feasible up to 100 m depth or little more).

• Option 1: smaller horizontal-axis wind turbines rated at 6 MW in 2025 and 12 MW in 2050, on foundations laid on the sea bottom up to 100 m water depth.

• Option 2: smaller vertical-axis wind turbines rated at 6 MW in 2025 and 12 MW in 2050, on foundations laid on the sea bottom up to 100 m water depth.

• Option 3: horizontal-axis wind turbines of the same size (rated at 12 MW in 2025 and 24 MW in 2050), but on floating foundations in waters up to 500 m deep.

• Option 4: kite vertical-axis wind turbines rated at up to 100 MW in 2050, on foundations laid on the sea bottom up to 100 m water depth.

The first two alternative options could be seen as rather obvious technology gaps, whilst the last two, if feasible, would turn out as real technological breakthroughs. The following sections describe each of the four alternative technological options mentioned above, as well as the main highlights that have come out from their comparison with the reference technology on the basis of the set of criteria and indicators put forth by the RS 2b Report. Lastly, a full overview of the results of these comparisons and the reasons underlying them, is appended at the end of this chapter. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

No influence



38

4.2 Option 1: smaller horizontal-axis wind turbines

4.2.1 Technology gap description It has been foreseen that the baseline technology will lead to very large sizes of wind turbines (12 MW of unit capacity with 160 m of rotor diameter in 2025, and 24 MW with 250 m of rotor diameter in 2050). Such huge dimensions will be conditional upon a full revolution in materials and manufacturing techniques, not to mention installation issues, but whether and when such breakthroughs could really happen is still difficult to see. Even the RS 1a Report has pointed out no outstanding development that can be predicted to have enough likelihood of being achieved in the short or medium term. Moreover, even supposing that new materials and techniques became available within the 2025-2050 time frame, it does not seem sure that the investment cost of offshore wind farms could, in this case too, continue to decrease at the rate calculated from the learning curves given in the report, as such new, not yet well-known materials and construction techniques could well bring about higher costs than is expected on the basis of current technology and machine sizes. With this in mind, it would seem reasonable to take into account an option where offshore wind farms would be made up of smaller horizontal-axis wind turbines, for instance machines with 6 MW capacity and 130 m rotor diameter in 2025, and 12 MW and 160 m rotor diameter in 2050. The most obvious consequence of this would be many more machines being set up for the same wind farm capacity, with thicker occupation of the sea area and heavier visual impact (figure 4). The wind turbine foundations would, of course, remain of the same type as with the baseline technology, namely fixed foundations in up to 100 m deep water. Also the other parts of the wind farm should, more or less, remain the same as with the reference technology.

4.2.2 Technology gap influence on criteria and indicators Environment. Since this technological option would make it necessary to manufacture larger numbers of wind turbines to install the same overall capacity, the consumption of primary energy of whatever kind would be higher in this process. Therefore, also the contribution to climate change and the impact on the ecosystem would be heavier. Economy. Since a larger number of smaller units would be used, the average generation cost of offshore wind farms could become higher to some extent, as less tall machines capture lower wind, and therefore give less energy production. Being wind turbines smaller, the size of wind turbine factories could often be smaller, too, thus reducing the use of land at each manufacturing site. The number of factories and the number of related jobs would likely increase, with ensuing benefits to employment. From the standpoint of utilities, the overall investment cost would remain about the same (more units of cheaper technology), but the plant construction time would become a little longer. Dispatching would become more flexible, as wind farms would be more numerous and could be scattered among more sites with different wind conditions over time. Social aspects. The management of wastes would become harder owing to the larger number of wind turbines to be disposed of at the end of their lifetime. Smaller machines would be less suitable for incorporating new technological developments and breakthroughs. The greater number of machines would certainly increase their visual and environmental impact, even at locations far from the shoreline, hence there would be more involvement of the public opinion, but often less favourable acceptance of new projects. The slightly higher unit energy (kWh) production cost would affect consumers. The operation and maintenance of smaller and more traditional machines would require less skilled personnel. As said, given the same site and total plant capacity, the impact on the landscape would be heavier due to the larger number of units, even though the machines would be less tall. The noise during operation would be nearly the same as with the

39

baseline technology, while the annoyance caused by land and sea traffic during plant construction would increase owing to the larger number of machines to be carried to sites.

figure 4 Visual comparison between two existing offshore plants: a 40 MW wind farm with 20 machines of 2 MW capacity (Middelgrunden, Denmark) and a 10 MW wind farm with 2 machines of 5 MW capacity (Beatrice, United Kingdom). The influence of growing unit size is evident.

4.3 Option 2: smaller vertical-axis wind turbines

4.3.1 Technology gap description An alternative to smaller horizontal-axis wind turbines could be the use of vertical-axis wind turbines of the same rated power, namely 6 MW in 2025 and 12 MW in 2050. Vertical-axis wind turbines have never been installed at offshore locations yet, but in principle nothing would prevent their adoption. Modern vertical-axis wind turbines can have different types of rotor, but the Darrieus rotor with curved blades (the so-called eggbeater rotor) seems to be the best suited to machines of significant size (figure 5). This rotor has been studied for many years and tried on several prototypes and also on small batches of series-produced machines. The largest unit so far built has been a prototype rated at 4 MW with an overall rotor height of 100 m, which was tested in Canada in the 1980’s. Unfortunately, vertical-axis machines have sometimes shown structural and vibration problems that have hampered their success on the market, jointly with the contemporaneous development of reliable and efficient horizontal-axis machines, but this does not mean that these problems could not be solved if enough resources were devoted to improving the vertical-axis technology. The advantage of vertical-axis machines comes mainly from the fact that all the heavy mechanical parts such as gearboxes, electrical generators etc. are located at ground, or however at low, level instead of being placed in a lofty nacelle borne by a tall tower. Moreover, they need not be oriented to the direction of the wind. In principle, a Darrieus machine of 6 MW rated power would be about 140 m in overall height, against the about 200 m that the tip of a blade of a 6 MW horizontal-axis turbine would reach when turning. Likewise, a Darrieus machine of 12 MW would be 170 m high, against the 220-240 m that would be reached by the blade of a 12 MW horizontal-axis unit. Hence it is clear that the vertical-axis technology could well hold prospects of having a lower visual impact as compared to the horizontal-axis machines of the same capacity, not to mention those considered as the baseline technology. The option of off-shore wind farms with vertical-axis Darrieus machines is therefore to be taken into consideration in this comparative analysis, albeit with sizes limited to 12 MW by 2050. The other parts of the wind farm should, also in this case, remain about the same as with the reference technology. Particularly, the

40

foundations are assumed to be of the same type as for the baseline technology, namely fixed foundations in up to 100 m deep water.

figure 5 A modern vertical-axis wind turbine equipped with a Darrieus rotor with curved blades.

4.3.2 Technology gap influence on criteria and indicators Environment. As with smaller horizontal-axis turbines, also this technological option would make it necessary to manufacture larger numbers of wind turbines to have the same overall capacity on line. Therefore, the consumption of primary energy of whatever kind could be higher in this process, too, but this increase could be offset, at least in part, on account of the simpler structure of machines with Darrieus rotors. The overall impact of the manufacturing process on the ecosystem would thus be a little greater than with the baseline technology, but less than with the previous option of smaller horizontal-axis machines. Economy. Since a larger number of smaller units would be used, the average generation cost of offshore wind farms could become higher to some extent, because less tall machines capture lower winds, and therefore give less energy production. This consequence would be more severe in this case than with horizontal-axis turbines, as the equator of Darrieus rotors would be at a lower height than the hub of a horizontal-axis rotor of the same power. The size of wind turbine factories could be smaller in this case, too, thus reducing the use of land at each manufacturing site. The number of factories and related jobs would likely increase, with ensuing benefits to employment. From the standpoint of utilities, the overall investment cost would remain the same (more units of cheaper technology), but the plant construction time would become a little longer. Plant dispatching would become more flexible, as more wind farms would be scattered at sites with different wind conditions. Social aspects. The management of wastes would be harder owing to the larger number of wind turbines to be disposed of at the end of their lifetime. Vertical-axis machines are no new concept and would not be very suitable for incorporating new technological developments and breakthroughs. The greater number of machines would certainly increase their visual and environmental impact, even at locations far from the shore, hence there would be more involvement of the public opinion. The acceptance of new projects by the public might be a little better than for horizontal-axis units, because turbines would be less tall and visible. The slightly higher unit energy (kWh) production cost would affect consumers. The operation and maintenance of simpler machines would require less skilled personnel and would pose fewer hazards because all mechanical and electrical parts are located at the turbine base. Conversely, this feature could make terrorist attacks easier. Given the same site and total wind farm capacity, the impact on the landscape would be heavier due to the larger number of machines, but lower because of their lower height. The noise during operation would be nearly the same as with the baseline technology, while the annoyance caused by

41

land and sea traffic during plant construction would increase owing to the larger number of machines to be carried to the site.

4.4 Option 3: same horizontal-axis wind turbines on floating foundations

4.4.1 Technology gap description The current technology of foundations fixed to the sea bottom limits the installation of offshore wind farms to rather shallow waters, as these foundations have so far been made in sea areas no more than 45 m deep and are unlikely to become economically feasible beyond 100 m water depth even in the long term. On the other hand, the possibility to have recourse to deeper waters (e.g. up to 500 m) would widen considerably the sea areas where wind farm sites could be singled out, and would also allow to move wind farms farther off the coast (at least as far as it would be compatible with the maximum affordable length of grid-connecting lines), thus reducing problems with visual impact and other environmental issues. Also the concerns about the interference of plants with fishery and navigation routes would be felt much less. Wind turbines and their floating foundation platforms could be manufactured and assembled entirely at seaside factories, even at shipbuilding yards etc., thus avoiding most land transportation problems, and the full turbine-and-platform unit could then be towed to the site and moored in place. The work on site would mainly consist of the laying of mooring lines, anchors and grid-connection cables. This advantage could make it possible to install wind turbines of very large sizes, up to the capacity foreseen for the baseline technology (12 MW in 2025 and 24 MW in 2050). Although no full-sized floating wind turbine has been demonstrated yet, a number of studies have been under way on the dynamic behaviour of floating wind turbines, which has peculiar issues to be analysed in respect of fix-based onshore and offshore machines. A few different technical solutions have already been proposed for floating platforms worldwide, as shown in figure 6. It is too early to judge which of them could be the best suitable and other contrivances might well come up in the future. In any case, the success of floating wind turbines could open a major breakthrough towards the spreading of offshore wind farms of very large capacity. With this in mind, this analysis also takes into consideration, as a technological option, horizontal-axis wind turbines rated at 12 MW in 2025 and 24 MW in 2050 (i.e. the same unit capacities as with the baseline technology), mounted on floating foundations in waters that could likely reach up to 500 m depth. In principle, the rest of the wind farm could remain about the same as with the other options, with the exception of likely longer grid-connecting lines.

figure 6 – Three different designs of floating foundations proposed for offshore wind turbines. From left to right: the spar-buoy foundation by Hydro (Norway); the semi-submersed Dutch Tri-Floater by ECN et al. (the Netherlands); the TLP (Tension Leg Platform) by NREL (U.S.A.).

42

4.4.2 Technology gap influence on criteria and indicators Environment. Since this technological option considers wind turbines of the same size as the baseline technology, but these turbines would be mounted on floating structures simpler than the heavy foundations that would be needed in deep waters, the consumption of primary energy of whatever kind for building the plants would be lower in this case. Therefore, also the contribution to climate change and the impact of plant construction on the ecosystem would be lower. Economy. Given the same wind turbine size, the use of foundations that could be simpler and cheaper than the fixed ones in deep waters could make for lower average generation costs of offshore wind farms. Since the number of wind turbines manufactured would remain the same, but simpler foundations could be built at seaside places, it is likely that the total number of jobs would neither decrease nor grow in this case. For the same reasons, and also considering the site work to be carried out on mooring devices, the overall investment cost would remain nearly the same. The plant construction time could be shorter. Dispatching would benefit from the fact that wind farms could be located in sea areas farther from the coast, where windiness is better and definitely more steady. As said above, all these factors could act in favour of lower unit energy costs. Social aspects. The management of wastes would be less difficult, as floating wind turbines could be dismantled more easily at the end of their lifetime (it would be enough to cut moorings and tow units back to shore). Most of floating platform technology would in all likelihood be derived from oil drilling platforms, so that few totally new concepts would have to be devised to get breakthroughs in this application. The greater distances of machines from the shore would diminish their visual and environmental impact, thus bringing about less concerns and involvement of the public opinion. The acceptance of new projects would thus be more favourable, because turbines would be less visible and interfering with ships and fishing boats. On the contrary, since floating wind turbines could be sunk, the potential of terrorist attack would be higher. The somewhat lower unit energy (kWh) production cost would also affect consumers positively. The operation and maintenance would require some specially skilled personnel as far as submersed parts and moorings are concerned. The noise during operation would be nearly the same, but its annoyance would be less owing to more remote locations. Also the annoyance caused by land and sea traffic during plant construction would be less, as the units would be built on shore and then towed to the site.

4.5 Option 4: kite vertical-axis wind turbines

4.5.1 Technology gap description This case refers to a fully innovative concept of wind turbine: the kite wind generator, which has recently been put forward as a possible alternative to replace traditional horizontal and vertical-axis wind turbines as unit capacities grow further. Apart for some small-scale trials, this new concept has not yet been demonstrated as feasible in the field and how and when it will be implemented is still uncertain. However, its degree of innovation is remarkable, so that it is worth being taken into consideration as a possible breakthrough at least in the very long term, namely by 2050. The blades of the traditional vertical-axis wind turbine are replaced by a large number of kites, made of semi-flexible airfoils, which fly under the thrust of the wind along a circular path at heights above ground that may be considerable, up to 800 m. The kites pull as many booms rotating on a horizontal plane, which in turn power a central vertical shaft driving the electrical generator. Kites are fastened to booms by a couple of cables tied to their tips, which are also used to control the motion and have the kites follow the desired track. In principle, even units of very large capacity could be built, up to 100 MW of rated power and with a diameter of the circular path of 800-1000 m at ground level (figure 7). These kite-driven wind turbines could in principle be installed on land as well as offshore in waters up to 100 m deep, as with the baseline technology wind turbines. Their large unit capacity could allow to set up fewer units to have the same overall wind farm capacity, but the space taken up by each unit at low level would obviously be much wider and should be signalled in a proper way. What is more, the annual energy

43

production of these wind farms could in principle be greater than that of customary plants, thanks to the very strong winds that could be tapped by kites at their high altitudes. The construction work should not make it necessary to transport very large and heavy components either by land or by sea. The foundations should be fixed to the sea bottom and could in principle be similar to those of large wind turbines of the baseline technology. The main practical aspect not yet fully explained seems to be how to operate so many kites under all wind conditions. With a view to a possibly successful outcome of ongoing and future studies and experiments, this technology is assumed in this analysis as the most advanced technological option, which might even result in a striking breakthrough of wind technology. Reference is made to 100 MW units, with 800-1000 m diameters at low level, in waters up to 100 m deep.

figure 7– Artist’s views of two types of kite wind turbine with multiple airfoils.

4.5.2 Technology gap influence on criteria and indicators Environment. This technological option considers generating units that have a remarkably larger size than the baseline wind turbine technology. Nevertheless, these units would be built in a fully different way: the whole structure would be big, but could be made up of many simple and rather conventional components. The foundations would be fixed and, in principle, somewhat similar to those of the baseline technology. Considering all that, the consumption of primary energy for building the plants could turn out a little lower. Owing to fewer, more distant units being set up, even though each unit would be much more cumbersome at sea level, the contribution to climate change and the impact of plant construction on the ecosystem could be estimated as lower. Economy. The use of fewer, larger units made up of conventional structures, and the potentially greater energy production that could come from kites flying high in stronger winds, could result in lower average generation costs. Fewer wind turbines with structures made up of rather common elements, are unlikely to bring more jobs and could even decrease their number. For the same reasons, the overall specific investment cost (euro/kW) would, in all likelihood, be lower. The plant construction time and start-up time would, on the contrary, be a little longer. Dispatching would benefit from the fact that these wind farms could provide the system with firmer power, because they would benefit from very steady winds at high altitude. On the other hand, fewer units would make dispatching less flexible. The unknown behaviour of kites over time makes any estimate of plant availability more difficult. Social aspects. The management of wastes would be affected in a favourable way, as the structures that would have to be dismantled and disposed of at the end of the plant lifetime would be rather conventional. Notwithstanding this, the overall concept is quite innovative, particularly from the viewpoint of aerodynamics; therefore it is open, in principle, to many new developments and breakthroughs. The high altitude (up to 800-1000 m) at which kites could fly, would make these units visible from very far, even though their visual impact on observers on the ground could be reduced considerably by distance. The

44

impact on sea navigation and flight would be heavy and would strike and concern the public opinion. The acceptance of new projects might thus be more difficult, in spite of their being far from the shore. Conversely, the possibly lower unit energy (kWh) production cost would affect consumers positively. The operation and maintenance should not cause more noteworthy hazards, as units would be fewer and their gears would be located at rather low level. It is not easy to foresee whether any special skills would be needed to handle kites. The noise from high flying kites should not be an issue. Also the annoyance caused by land and sea traffic during plant construction would be less, because only relatively small components would have to be transported on land, while the generating units would be assembled on site.

45

4.6 Results of comparison of the four technological options with the baseline technology assumed for offshore wind farms, in respect of the various criteria and relevant indicators.


UNIT Smaller size Horizontal axis

Smaller size Vertical axis

Same size with floating foundation

Kites Vertical axis

Smaller size Horizontal axis

Smaller size Vertical axis

Same size with floating foundation

Kites Vertical axis

1 ENVIRONMENT1,1 RESOURCES1.1.1 Energy Resources1.1.1.1 Fossil primary energy Total consumption of fossil resources (LCIA) min MJ/kWh

�� more units manufactured

more units manufactured, but simpler structure

simpler structure, not supported by foundation on sea bottom

fewer and larger units

1.1.1.2 Other non-renewable energy Total consumption of uranium (LCIA) min MJ/kWh

��




see above, no increse in fossil fuel use


min kg(Sb-eq.)/kWh

��

see above, likely more nuclear in energy mix



see above, also nuclear energy is less

1,2 CLIMATE CHANGE1.2.1 Global warming potential (LCIA) min kg(CO2-eq.)/kWh


more units manufactured, simpler structure



1,3 IMPACT ON ECOSYSTEMS

1.3.1 Impacts from Normal Operation1.3.1.1 Biodiversity (land use) Impacts of land use on ecosystems (LCIA) min PDF*m2*a/kWh

�� smaller factories smaller factories smaller factories smaller factories

1.3.1.2 Ecotoxicity Impacts of toxic substances on ecosystems (LCIA) min PDF*m2*a/kWh


more units manufactured



1.3.1.3 Acidification and eutrophication Impacts of air pollution on ecosystems (LCIA) min PDF*m2*a/kWh





1.3.2 Impacts from Severe Accidents1.3.2.1 Release of hydrocarbons Large release of hydrocarbons (RA) min t/kWh

�� no influence no influence no influence no influence

1.3.2.2 Land contamination Catastrophic land contamination (RA) min km2/kWh�� no influence no influence no influence simpler technology

1,4 WASTES



min kg/kWh�� no influence no influence no influence simpler technology

1.4.2 Medium and High Level Radioactive Wastes to be stored in Geological Repositories

Total amount of medium and high level radioactive wastes to be stored in geological repositories (LCA)

min m3/kWh


Trend of indicators as compared to the baseline technology Reasons for the trend

46

ECONOMY

IMPACTS ON CUSTOMERS

Price of electricity Average generation cost min �/MWh





IMPACTS ON OVERALL ECONOMY

Employment Direct jobs max Person-years/GWh




fewer units of simpler technology

Autonomy of electricity generation Medium to long term independence from foreign imports, based on domestic energy storage and/or resources

max Ordinal


IMPACTS ON UTILITY

Financial Risks

Capital investment exposure Total capital cost min �

��

more units, of less expensive technology

more units, of less expensive technology

no foundation on on sea bottom, but need of deep-water mooring

fewer units of simpler, less expensive technology

Impact of fuel price changes Sensitivity to fuel price changes min Factor�� no influence no influence no influence no influence

Risk due to changes in boundary conditions

Construction time min Years

��

more units to manufacture and install

more units to manufacture and install

simpler structure towed to place

simpler structure, but longer assembly and start-up

Operation

“Merit order” for dispatch purposes Total average variable cost or “dispatch cost” min �cents/kWh

��

more units with higher kWh production cost


simpler structure, no foundation on sea bottom, lower kWh cost

units exploit steady winds at higher altitude

Flexibility of dispatch Composite indicator max Ordinal

�� more units located in different places

more units located in different places

units located farther from shore in better winds

fewer, larger units in the same place

Availability Equivalent Availability Factor max Factor

�� same machine availability

same machine availability

same machine availability

unknown behaviour of kites over time

47

SOCIAL ASPECTS

SECURITY/RELIABILITY OF ENERGY PROVISIONPolitical Threats to Continuity of Energy ServiceDiversity of primary energy suppliers Market concentration in the supply of primary

sources of energymin Ordinal scale


Waste management Probability that waste storage facilities will not be available

min Ordinal scale



simpler structure, no foundation on sea bottom fewer units

Flexibility and Adaptation Ability to incorporate new technological developments and breakthroughs

max Ordinal scale

��

more traditional technology needed in smaller wind turbines

vertical-axis technology is not a new concept, needs only more development

most technologies from oil platforms

very innovative concept open to possible new developements

POLITICAL STABILITY AND LEGITIMACYPotential of Conflicts induced by Energy Systems.


min Ordinal scale

�� more units installed more units installed

machines farther from shore, hence less visible

high devices that can be seen from very far

Willingness to act (Mobilization Potential)



Ordinal scale




Reliance on participative Decision-making Processes



Ordinal scale




Citizen Acceptance of the System Empirical survey results on average citizen acceptance of specific energy technology

max Ordinal scale




SOCIAL AND INDIVIDUAL RISKS

Expert-based Risk Estimates for Normal OperationReduced life expectancy due to normal operation

Mortality due to normal operation (EIA+LCA) min YOLL/kWh

�� more, but lower units installed

more units, but gears are located at low level same height

fewer units with gears located at low level

Non-fatal illnesses due to normal operation

Morbidity due to normal operation (EIA+LCA) min DALY/kWh




Expert-based Risk Estimates for accidents

min

Expected Health effects from accidents Expected Mortality due to severe accidents (RA) min Fatalities/kWh




Maximum consequences of accidents Maximum credible number of fatalities per accident





Perceived Risks

Perceived risk characteristics for normal operation


min Ordinal scale


more units, but gears are located at low level

less visible, fewer chances of collision


Perceived risk characteristics for accidents


min Ordinal scale


more units, but gears are located at low level

less visible, fewer chances of collision


48

Terrorist Threat

Potential of attack Potential for a successful attack (RA) min Ordinal scale

��

same concept as larger horizontal-axis turbines

gears are at low level and therefore much easier to reach

floating foundation is rather easy to sink

big rotating structure with kites at 800 m above water

Effect of a successful attack Likely potential effects of a successful attack (RA) min Expected number of fatalities

��

no man on machines in normal operation




Proliferation Potential for misuse of technologies and substances within the energy chain

min Ordinal scale

��





QUALITY OF LIFE

Socially compatible development

Equitable life conditions Share of the effective electricity costs in a social welfare receiver budget

min %

��

more units, hence likely higher kWh cost

more units, hence likely higher kWh cost

no support on sea bottom, better wind, hence likely lower kWh cost

fewer units of high productivity, hence lower kWh cost

Work quality Weighted index of work qualifications max Factor

��

more traditional technology than in larger wind turbines

same skills as for horizontal-axis turbines of the same size

need for some more special skills, also for deep-water mooring

these very innovative devices may ask for some special skills

Effects on the Quality of Landscape and Residential AreaEffects on the quality of the landscape Functional and aesthetical impact of energy

infrastructure on landscapemin Ordinal scale

��

more units cause thicker occupation of sea areas

same impact as smaller horizontal-axis, but somewhat lower units

units are farther from shore and less visible

fewer and lower structures - kites are very high (800 m)

Noise exposure Number of residents feeling highly affected by noise caused by the energy facility or transports to and from the energy facility

min Ordinal scale

�� about the same noise

about the same noise

same noise at sea - floating units are mostly built at seaside places

lower noise from kites flying very high

Contribution to traffic Total traffic load (LCA mainly) min to be determined

�� more units to be transported

more units to be transported

floating units are mostly built at seaside places

structures assembled on site or at seaside places

49

4.7 References [1] European Wind Energy Association (EWEA): "Wind Energy - The Facts", report in 5 volumes,

Brussels, 2004, available on site www.ewea.org. [2] International Energy Agency: “IEA Wind Energy Annual Report 2007”, July 2008, available

from the Executive Committee of the IEA Wind Implementing Agreement, www.ieawind.org. [3] BTM Consult ApS: "International Wind Energy Development - World Market Update 2007 -

Forecast 2008-2012", March 2008, available for purchase from www.btm.dk. [4] European Wind Energy Association (EWEA): “Delivering Offshore Power to Europe”,

Brussels, 2007, available on site www.ewea.org. [5] European Wind Energy Association (EWEA): “Pure Power – Wind Energy Scenarios up to

2030”, Brussels, 2008, available on site www.ewea.org. [6] S. Butterfield, W. Musial, J. Jonkman, P. Sclavounos: “Engineering Challenges for Floating

Offshore Wind Turbines”, October 2005, paper available on site www.nrel.gov. [7] M. Canale, L. Fagiano, M. Milanese: “Power Kites for Wind Energy Generation”, December

2007, IEEE Control Systems Magazine”.

50

5 PV Technology

Fabrizio Paletta, CESI RICERCA, SSG Department

5.1 Technology credited in RS1a for 2025-2050 As well known, the basic unit of a photovoltaic (PV) system is the cell, which is in general a semiconductor device converting the solar radiation into electricity. PV cells are low voltage (0.5 – 1 Volt) and high current devices. More cells, connected in series and in parallel, form a PV module which has typical power ranging from few watts up to 300 W. Nowadays the most used size is 170-230 W (obtained with 72 silicon cells 150 x 150 mm), which corresponds to module dimensions as 1500 mm x 1000 mm and to a weight of 15-18 kg. Then a group of modules create a string and finally many strings create the PV field. PV systems can be off grid or grid connected. The world PV market is facing a boom that is related mainly to the grid connected application, by far the most popular systems in the developed world, mounted on roofs of houses, integrated on building facades or installed at ground level in large power stations. Whichever kind of application is considered, there is a diffused consensus among citizens that solar energy generation plants will have a prominent role in electricity production from now on, because they are simple, robust, reliable and safe. The solar energy resource is very abundant on the earth, and differently from wind, is available everywhere: just to say, to cover south oriented roofs of Europe should be enough to produce the whole electricity needs (3 kW need 24 m2 of surface) , or equivalently only 0,7% of the total land of EU could cover all the electricity demand, taking into account that 7-8 m2 of module are sufficient to assemble a 1 kW system. Practically, the exploitation of this resource has been limited by many technical and non technical barriers and drawbacks: availability of basic materials for the cells manufacturing, low world production capacity, high energy consumption in the fabrication processes, low conversion efficiency have till now limited the PV potential but the foreseen improvements in industrial processes and change of technologies will overcome these barriers and will contribute to reduce the high cost of PV; also the modest level of acceptance worldwide, the need of using lands with precise characteristics of exposition and solar radiation, no way to easily storage the energy produced and finally the overall cost are further obstacles. On the other side, PV has a good complementarity with other sources (wind or traditional), can be used and implemented in various kind of systems (from small systems of few kWp for houses to large scale PV plants up to multimegawatt solutions) and produces electricity in very clean way, without any emissions of gas. While generation costs are expected to fall down, new material and devices are appearing on the market, as a consequence of the assessment of international work in the field of research with the promise of longer lifetimes, higher reliability combined with higher efficiencies. All these concepts and facts seem to suggest that in spite of some controversial aspects, a strong penetration of PV, as one of the main global energy sources for future, needs still great improvements in technology: higher efficiencies of cells and modules, and lower costs per watt and produced watt-hour are essential and next decade will decide the sort of this fundamental resource. Market expansion from year 2000 to 2008 shows a positive trend that forces to be optimistic. At the end of 2000 there was a capacity of 1200 MW while the same indicator for 2007 has grown to 9200 MW(annual installation from 300 MW in 2000 grew to 2400 MW in 2007). Installations of PV systems have been increasing at an annual rate of minimum 35%/year in the last ten years. This large expansion of PV has been strongly favoured by some effective national and regional market support programmes, the so-called feed-in tariffs that generate the very successful story of Germany and Spain markets and by the consequent significant increment manufacturing capacity in these countries. “The solar generation V – 2008” just published proposes a scenario that gives to solar electricity a major role in term of contribution to the future global electricity supply. The scenario itself is in fact delivered in two versions, advanced or moderate that differ for the growth rate. The detailed projections for 2030 consider the following figures (table 1):

51

table 4 Projections to 2030 PV cumulative capacity (GW) 1860 Electricity production (TWh) 2600 Cost of solar electricity (c�/kWh) 7 – 13 (irradiation from 900 to 1800 h/y) CO2 savings 9000 million tonnes

: The global electricity demand from PV should be so high as 13.8% of the total. Moreover, in environmental terms, the CO2 savings is based on the assumption that it is possible to save 0.6 kg of CO2 for any kWh produced by a PV generator, so the figure above is equivalent to the output of 450 coal fired power plants. Other considerations must be done regarding environmental impact, social aspects and economics. As said, it would be ideal to have PV technology able to demonstrate high efficiency combined with competitive costs. But low efficiency with very low costs could be a sufficient condition for a dramatic increase of PV market. Moreover, there is a different economic approach of utilities which compare generation cost of electricity from PV with the similar costs of other technologies, and of consumers that pay more attention to the cost of installation of the PV system, to the output power over time and compare the consequent final costs they paid to retail costs of electricity they buy. Environmental consideration evidence that PV is a very friendly technology because, when operating, PV systems do not produce air emissions or greenhouse gases, in full synergy with what reported in Kyoto protocols, then there are not liquid wastes while solid wastes will be produced only at the end of life of the plant when it will be dismounted for starting of the recycling phase. Finally, no noise is generated. The social acceptance of PV is different from country to country. Negative recurring concepts well diffused regard land use. This is a false problem because in most cases engineers use rooftops, facades, parking structures or land already damaged and do not occupy valuable surfaces. The special case of very large scale PV systems (multimegawatt plants) need large extensions of land, (about 20,000 m2 for any MW installed) but impact on wildlife can be strongly reduced with proper choices, using for example deserts or similar unused lands. Finally, PV can produce good effects on occupation: PV in Germany has generated about 30,000 new jobs

5.2 PV MODULE TECHNOLOGY The term “PV modules” actually embraces a large variety of PV technologies, based on different semiconductor devices. The main distinction is between PV modules made of crystalline semiconductor (single and multi crystalline silicon) and thin films (amorphous silicon, cadmium telluride, copper indium diselenide). In 2007, currently crystalline silicon technology still dominates the market, while thin-films represent from 6 to 12% in terms of installed capacity, according to different sources.

• Crystalline silicon PV modules Wafer-based crystalline silicon currently represents the main technological route for the production of PV modules and it is envisaged to remain so for many years. Crystalline silicon modules are typically produced by growing ingots of silicon, slicing the ingots to make solar cells, electrically interconnecting the cells, and encapsulating the strings of cells to form a module. The main advantages of this technology can be summarised as follows:

- Established technological background (derived from the electronic industry), availability of the source, high demonstrated reliability.

Among the drawbacks reported: - Overall silicon feedstock of affordable quality and price is still relatively low, material costs are higher

compared to thin-film modules, current silicon feedstock production is energy intensive. The two main typologies of crystalline silicon are: single crystalline silicon (c-Si) and multi-crystalline (mc-Si). Sc-Si is characterised by atomic layers all oriented in the same direction in a single silicon crystal. Multi-crystalline silicon is made of a set of single-crystalline, small-area, sc-Si clusters. Clusters all oriented in different directions, giving the aesthetical effect of non homogeneous reflection of the

52

More recently, ribbon technologies have been developed. In this technology wafers in form of ribbons are pulled directly from the silicon, without the production of the ingot and the need to cut it in wafers. This technology has similar efficiencies like mc-Si but a much better utilization rate of silicon feedstock.

• Thin film PV modules Thin film PV (TFPV) is based on a complete different manufacturing approach: instead of producing an ingot and then cutting it into wafers, thin films are obtained by depositing extremely thin layers of photosensitive materials on a low cost backing such as glass, stainless steel or plastic. The first thin film produced historically was amorphous silicon (a-Si). At present,, other thin film technologies have been developed in the area of II-VI semiconductor compounds, i.e. Cadmium Telluride (CdTe) and Copper-Indium-Diselenide (CIS). Adding small amounts of Gallium to the absorbing CuInSe2 layer (CIGS modules) improves the efficiency of the device. Layer thickness of thin films is very low, ranging from 40-60 �m of amorphous silicon down to less than 10 �m of CdTe. Therefore, much less material is needed to produce cells / modules. The main advantages of thin films are:

• Low consumption of raw material • Suitable for building integration, due to flexibility and better appearance of the modules • High automation of production (less labour intensive) • TFPV can be integrated on various type of useful substrates, such as plastic and glass and are ideal

for BIPV application, both as power sources and structural components The disadvantages commonly reported are:

• Lower efficiency rates with respect to crystalline • Less experience on the modules’ lifetime performance • Only production units for CdTe have capacities comparable to the ones of Silicon (some 100 MW

scale factories). • TF is a less mature technology than Si, but is expected to gain fastly higher share of the market Thin-

film photovoltaic technology has an inherent low-cost potential because the manufacturing process of cells and modules require small amounts of PV materials, can be fully-integrated and gives high throughputs. At present, device quality and module efficiency are still low, and the improvement of the quality and stability of transparent conductive oxides (TCOs) are necessary, together with higher throughputs and yields, to permit an accelerated market development of cost-effective and more efficient thin film photovoltaic. table 5summarizes efficiency and application of the state-of-the-art PV technology (2008)

table 5 Technical parameters of current PV systems

Wafer-based c-Si Thin films

sc-Si mc-Si a-Si CdTe CIS

Module efficiency (%) 14-19 12-15 6-7 9-11 9-10

Main applications Centralized and distributed grid-

connected systems (incl. BIPV);

Remote industrial and rural

Centralized and distributed grid-

connected systems (incl. BIPV);

Remote industrial and rural

Consumer products; off-grid rural;

building integration

Grid-connected systems, included

centralized

Building integration

Grid-connected systems;

Building integration

An attempt of figuring out the evolution in solar cell technology has been made in NEEDS Project’s RS 1a Final Report on PV Technology (Deliverable No. 11.2 – RS 1a). Prospective for technology as of 2025 and 2050 were made out in this report from three different scenarios, called roadmap 1, 2, 3 corresponding to a worldwide different level of penetration of PV and to a different contribution of the various technologies to manufacture a solar cell.. These roadmaps consider different rates of growth (very optimistic, realistic, and pessimistic vision) and were, in turn, chosen among a number of scenarios shaped by the IEA (International Energy Agency), the EPIA roadmap, the EC/PV-TRAC (A vision for photovoltaic technology), the US Photovoltaic industry (Roadmap to 2030 and beyond), published within 2006.

53

A summary of the main features of the three scenarios adopted by the RS1a report is given in table 6below, with data for year 2005 (reported in RS1a) updated to year 2008. .

table 6 Growth of PV capacity and PV electricity production worldwide up to 2050 under the three scenarios assumed by the RS 1a Final Report on PV Technology Installed PV capacity (GW) PV electricity production

(TWh) Global electricity share

(GW) Scenarios

2008 2025 2050 2008 2025 2050 2008 2025 2050

Pessimistic 13 170 530 18 238 742 0.05 0.6 2 Realistic 13 430 2400 18 602 3360 0.05 1.7 9.6 Very optimistic

13 1270 8900 18 1700 11800 0.05 5 30

For the sake of simplicity, table 7only focuses on the size trend that was drawn from the realistic scenario.

table 7 Main technological parameters for realistic option scenario Technology Module Efficiency (%) Module lifetime (Y) Cum. Installed capacity

(GW) 2008 2025 2050 2008 2025 2050 2008 2025 2050 Crystalline Silicon

14 20-22 22-25 25 35 40 >12 220 720

a-Si, CIS/CIGS. CdTe

9-10 15-20 18-25 25 30 35 <1 190 840

Novel devices DSC1

2-5 10 15 NA 10 10 0 15 600

Novel devices UHE2

30 35 40 NA 30 35 0 5 240

1Dye Sensitized Cells (Low Cost Devices) 2Ultra High Efficiency

In the analysis reported on in the following, the technology described in Table 4 has been taken as the baseline technology for evaluating the sensitivity, from the viewpoint of sustainability performance, of alternative technological options that can be envisaged for PGV systems in the same time frame, with a view to the subsequent Multi-Criteria Decision Analysis (MCDA) that will have to be carried out in RS 2b of the NEEDS Project. For this purpose, the variations in sustainability performance of the other technological options in respect of the baseline technology have been assessed by applying the set of criteria and indicators defined in the RS 2b Report “Environmental, Economic and Social Criteria and Indicators for Sustainability Assessment of Energy Technologies” (Deliverable No. D 3.1 - RS 2b). The technological options considered in this report can be summarised as follows:

• Baseline technology: it consists of roadmap 2 – realistic scenario with crystalline silicon 50%, thin films 45% and novel devices 5% share of the market for 2025 and 30%, 35% 35 % respectively in 2050.

As far as the three different “families” of PV technologies are concerned (i.e. crystalline Si, thin films and novel devices), they will likely co-exist all the way through, each expanding especially within its own most suitable market sector. What is largely foreseeable is that thin film technologies will be the first to expand, growing from 10% share of the market (the largest part of which is currently made up by amorphous Si) to approximately 45% thereof by 2025, with larger contributions by CIS and CdTe.

54

The timing for the expansion of the novel devices is of course harder to predict. Some famous experts of PV evaluations (among them, Dr. Winfried Hoffmann) predict a large market share of 35% for these technologies as early as 2030. However, we regard this to be a little too optimistic; therefore, in our market share scenario for 2025, we kept the novel devices at a more cautious 5%, putting off their expansion to 30% of the market share to 2050. We believe that this is more in line with current and projected R&D developments and with the time gap needed to move from laboratory research to mass production. However any long-term scenario is of course affected by a large degree of uncertainty. If a technological breakthrough in new concept technology already occurs in the period 2010-2020, this will obviously anticipate the diffusion of such PV devices • Option 1: it consists of roadmap 3 of the report – pessimistic scenario with: crystalline silicon 85%, thin

films 15% and novel devices 0% share of the market for 2025 and 50%, 45% 5 % respectively in 2050 • Option 2: it consists of roadmap 1 of the report – very optimistic scenario with: crystalline silicon 50%,

thin films 45% and novel devices 5% share of the market for 2025 and 15%, 35% 50 % respectively in 2050

• Option 3: same as option 2, but with a strong diffusion of very large scale PV plants in desert unused areas with size of plants in the range 100 MW – 1 GW or more.

While the first alternative, option 1, can be seen as a rather obvious technology stop and less of competitiveness of PV, the last two, if feasible, would turn out as real technological breakthroughs, thanks to the strong percentage attributed to the novel technologies and new plant solutions. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

No influence



5.3 Option 1: Pessimistic scenario, roadmap 3 of the report Rs1a

5.3.1 Technology gap description This option essentially mirrors the “best case” scenario drafted by IEA and OECD in their “Energy Technology Perspectives 2006” report (IEA/OECD, 2006). In this scenario, it is assumed that PV will at best cumulatively account for approximately 2% of the overall world electricity supply by 2050 (the latter being estimated by IEA at 35,000 TWh/a). If we assume an average irradiation of 1,400 kWh/(m2*a), implying that approximately 60% of the PV systems will be located in high-irradiation (i.e. 1,800 kWh/(m2*a)) Southern countries by 2050, and an improved average Performance Factor of 0.95, we obtain a cumulative installed capacity of approximately 530 GWp in 2050. This is a pessimistic scenario that essentially corresponds to assume that the current incentives for PV will not be supported long enough for the technology to ever become competitive with bulk electricity. In fact, according to the simulation made for this Road Map, the growth of the overall world PV market will only be in accordance with the predictions made in EPIA’s Solar Generation report till 2010, while it will already be severely stunted by 2025, when the cumulative installed capacity will start levelling off at 165 GWp More specifically, with respect to baseline technology, a much slower growth is foreseen for thin film PV, the market share of which only increases, in this scenario, to 15% in 2025, to then eventually reach 45% no earlier than 2050. In parallel, the gains in module efficiency are also much slower, with both c-Si and thin films struggling to improve significantly upon their current levels of performance by 2025, and eventually only reaching 18% efficiency by 2050. Of course, this prediction reflects the lower R&D funds likely to be

55

invested in these technologies in the event that they are not supported long enough for them to become economically competitive on a large scale. The market penetration of the novel technologies is also postponed to a much later time in this scenario, and even by 2050 they are only foreseen to account for a very small percentage of the total cumulative installed power, essentially reflecting a limited application of these new devices to niche market products. �

5.3.2 Technology gap influence on criteria and indicators Environment. Since this technological option would make it necessary to manufacture a smaller quantity of PV modules of any technology to satisfy a smaller market , the consumption of primary energy of whatever kind would be higher and, therefore, the contribution to climate change and the impact on the ecosystem of PV would be less significant. Economy. Since a smaller number of modules and PV systems would be used, the average generation cost of the PV installations could stay high, or higher of what expected and no really competitive with other sources. Being PV plant number at a minimum, there is a reduced use of land or buildings. The number of factories and the number of related jobs would likely have a small growth, with few benefits to employment. From the standpoint of utilities, the overall investment cost to update transmission and distribution grid would remain about the same Social aspects. The management of wastes would be less critical owing to the smaller number of PV systems to be dismounted and disposed of at the end of their lifetime. A reduce visual and environmental impact, hence there would correspond to a minor involvement of the public opinion, but often less favourable acceptance of new projects. The slightly higher unit energy (kWh) production cost would affect consumers. The operation and maintenance of smaller and more traditional plants would require less skilled personnel. As said, given the same site and total plant capacity, the impact on the landscape would be small due to the smaller number of units.. �

5.4 Option 2: Very optimistic scenario (Roadmap 1 of the report Rs1a)

5.4.1 Technology gap description For this optimistic option, bold annual growth rates are assumed from as early as 2010, and the trend is expected to keep growing in a quadratic fashion all the way through, topping out at 9,000 GWp in 2050. What this growth scenario implies is that by the mid-2030’s at the latest a large-scale energy storage infrastructure will have to have been developed. One option that is currently being considered in this sense is represented by electrolytically produced hydrogen gas. Integrated PV-storage systems such as these will be mandatory in order to guarantee the necessary stability of the network if PV is ever to provide more than 10% of the total electricity supply.

As far as the relative penetration of the three different types of technologies is concerned, this scenario is dominated by the predicted very rapid expansion of PV systems based on novel technologies after 2025 (following what can be referred to as a major “technological breakthrough”). These novel technologies are expected to grow as much as to eventually account for approximately 50% of the total PV market in 2050 (figure 8). In fact, it can be argued that the shift itself from a still limited share of total electricity production (3%) in 2025 to a very large diffusion of PV as a whole in 2050 (largest contributor among renewable energy technologies; 35% of total electricity production) heavily depends on the realization and diffusion of such new concept PV devices.

Once again, it is important to stress that this can only happen if adequate strategic research is funded in the period from today until 2025. If this requirement is not fulfilled and appropriate and affordable storage and energy load management instruments are not available, the installed capacity figures are not likely to be reached. �

56

PV Technology Market Share

0%10%20%30%40%50%60%70%80%90%

100%

2003 2010 2020 2030 2040 2050

Year

Mar

ket S

hare

Novel Devices

Other Thin Films

Thin Films

Silicon Thin Films

Crystalline Si

�

figure 8 Forecasted PV technology market share

5.4.2 Technology gap influence on criteria and indicators Environment. This technological option would make it necessary to manufacture a very large numbers of modules to have the foreseen overall capacity on line. Therefore, the consumption of primary energy of whatever kind could be higher in this process, too, but this increase could be offset, at least in part, on account of the higher efficiencies of manufacturing processes. The overall impact of the manufacturing process on the ecosystem would thus be greater than with the baseline technology. Economy. Since a larger number of PV plants would be used, the average generation cost of PV electricity could become lower to some extent, with higher energy production for the increased efficiency of cells and modules. The size of typical plants could be the same as in the realistic cases, thus increasing the use of land. The number of factories and related jobs would likely increase, with ensuing benefits to employment. From the standpoint of utilities, the overall investment cost would increase to prepare the grid to accept a very large contribution coming from this renewable source Social aspects. The management of wastes would be harder owing to the larger number of plants to be disposed of at the end of their lifetime.. The greater number of plants would certainly increase their visual and environmental impact, even at isolated locations, hence there would be more involvement of the public opinion. The acceptance of new projects by the public might be a little better The unit energy (kWh) production cost would be reduced an this would positively affect consumers. The operation and maintenance of large quantity of plants would require more skilled personnel and would pose some hazards related to electrical parts because of diffusion and size of plants Conversely, this PV surface occupation could make terrorist attacks easier. The impact on the landscape would be heavier due to the larger number of plants, but lower because of their good integration. The annoyance caused by land and sea traffic during plant construction would increase owing to the larger number of parts to be carried to the site. �

5.5 Option 3: Very optimistic scenario (Emerging concepts)

5.5.1 Technology gap description Option 3 has the same characteristic of option 2 but in this case, the contribution of very large scale PV plants, with size of plants in the range 100 MW – 1 GW or more, installed for example in desert, unused area that enjoy extensive exposure to sunlight, are considered. Strong international efforts are dedicated to these issues, which take advantage of the technological solutions adopted for large scale PV central stations (size 1-40 MW), now already existing and assume to use only very low value areas like for example the deserts. Many report show the feasibility and the impact of VLS-PV, offering a huge potential for socio-economic development as well as expected financial technical and environmental potentials. In any case, in industrialised countries we observe a strong trend toward larger systems, and at the end of 2007 more than 45 plats have nominal power higher of 5 MW (up to 40 MW under construction). In the

57

following table the proposed scenario for VLS PV application coming from prof. K. Kurokawa (TUAT, Japan) shows the contribution to PV generation of very large scale PV plant in the world from 2010 to 2100.

table 8Proposed VLS-PV roadmap (cumulative):

Year 2010 2020 2030 2050 2070 2100

World PV cum. 20 GW 140 GW 800 GW 10 TW 50 TW 133 TW

4 % 7 % 12.5 % 20 % 40 % 50 % LS-PV to VLS-PV

0.8 GW 10 GW 100 GW 2 TW 20 TW 67 TW

5.5.2 Technology gap influence on criteria and indicators Environment.. The overall impact of the manufacturing processes on the ecosystem would be smoother than with the option 2 technology. The size and special location of 20% of PV plants, would reduce the use of high value lands. Generated power can be used for water supply (desalination) or other productive use (agriculture, hydrogen production). Economy. Since a larger number of LS-PV and VLS-PV plants would be installed, accounting 20% of the total installed PV power cumulated in the world, the average generation cost of PV electricity could become lower to some extent, with higher energy production for the higher intensity of the solar radiation. With a price for modules of 7 c�/W a generation cost of 6 c�/kWh can be foreseen in desert area like Sahara with a global annual irradiation of 2700 kWh/m2/year. The number of factories for cell, module infrastructures production and related jobs would likely increase, with ensuing benefits to employment. From the standpoint of utilities, the overall investment cost would largely increase due to the need to transport for long distances the electricity produced. Social aspects. The management of wastes would be simpler owing to the size of plants to be disposed of at the end of their lifetime. The acceptance of new projects by the public might be good. The energy unit (kWh) production cost would be reduced an this would positively affect consumers. The operation and maintenance of large size PV plants would require more skilled personnel and would pose some hazards related to electrical parts because of diffusion and size of plants Conversely, this PV surface occupation could make terrorist attacks easier. The impact on the landscape would be heavier but with positive effects on the economy of the interested area..

58

��Results of comparison of the technological options with the baseline technology assumed for PV, in respect of the various criteria and relevant indicators�

�


UNIT Option 1 Option 2 Option 3

Explanation option1

Explanation option2

Explanation option3

1 ENVIRONMENT 1.1 RESOURCES 1.1.1 Energy Resources 1.1.1.1 Fossil primary

energy Total consumption of fossil resources (LCIA)

min MJ/kWh

��

less 'reduction of fossil fuel consumption

reduction of fossil fuel consumption

more reduction of fossil fuel consumption



min MJ/kWh

��

proportional reduction of nuclear power production



1.1.2 Mineral Resources (Ores)

Weighted total consumption of metallic ores (LCIA)

min kg(Sb-eq.)/kWh

��

less materials for enlarged solar field

more materials for enlarged solar field

more materials for enlarged solar field

1.2 CLIMATE CHANGE

1.2.1 Global warming potential (LCIA)

min kg(CO2-eq.)/kWh

��

les reduction of emission GH gases

more reduction of emission GH gases

more reduction of emission GH gases


1.3.1 Impacts from Normal Operation

1.3.1.1 Biodiversity (land use)

Impacts of land use on ecosystems

min PDF*m2*a/kWh

�� less solar fields

large solar fields

larger solar fields

59



Explanation option1

Explanation option2

Explanation option3

(LCIA)


min PDF*m2*a/kWh

��

less 'reduction of fossile fuel consumption

reduction of fossile fuel consumption

reduction of fossile fuel consumption



min PDF*m2*a/kWh

��

no influence no influence no influence


1.3.2.1 Release of hydrocarbons

Large release of hydrocarbons (RA)

min t/kWh

��


1.3.2.2 Land contamination Catastrophic land contamination (RA)

min km2/kWh

��


1.4 WASTES ��



min kg/kWh

��


1.4.2 Medium and High Level Radioactive Wastes to be stored in Geological Repositories

Total amount of medium and high level radioactive wastes to be

min m3/kWh

��


60



Explanation option1

Explanation option2

Explanation option3

stored in geological repositories (LCA)

2 ECONOMY ��


��


min �/MWh

��

small impact of PV generation

medium impact of PV generation

higher solar sharestrong cost reduction larger plants

2.2 IMPACTS ON OVERALL ECONOMY

��

2.2.1 Employment Direct jobs max Person-years/GWh

��

more jobs during construction and O&M



2.2.2 Autonomy of electricity generation

Medium to long term independence from foreign imports, based on domestic energy storage and/or resources

max Ordinal

��

minimal fossil fuel use

no fossil fuel use


2.3 IMPACTS ON UTILITY

��

2.3.1 Financial Risks ��

61



Explanation option1

Explanation option2

Explanation option3

2.3.1.1 Capital investment exposure

Total capital cost

min �

��

more materials for storage and enlarged solar field



2.3.1.2 Impact of fuel price changes

Sensitivity to fuel price changes

min Factor

�� minimal fossil fuel use




Construction time

min Years

�� less land requirement

more land requirement

more land requirement

2.3.2 Operation ��

2.3.2.1 “Merit order” for dispatch purposes

Total average variable cost or “dispatch cost”

min �cents/kWh

��


same price as baseline

large units with lower kWh production cost

2.3.2.2 Flexibility of dispatch

Composite indicator

max Ordinal ???

��


max Factor

��

same plants availability



3 SOCIAL ASPECTS

��


��


��

62



Explanation option1

Explanation option2

Explanation option3

Energy Service



min Ordinal scale

��


3.1.1.2 Waste management Probability that waste storage facilities will not be available

min Ordinal scale

��

no toxic substances used or disposal

no toxic substances use o disposal

no toxic substances use o disposal

3.1.2 Flexibility and Adaptation

Ability to incorporate new technological developments and breakthroughs

max Ordinal scale

��

new improvement still possible

new improvement still possible

new technology still under development

3.2 POLITICAL STABILITY AND LEGITIMACY

��



min Ordinal scale

��

63



Explanation option1

Explanation option2

Explanation option3

3.2.2 Willingness to act (Mobilization Potential)



Ordinal scale

��

reduced fluel consumption improves accettance of the plants

reduced fluel consumptionimprove accettance of the plants

reduced fluel consumption improve accettance of the plants




Ordinal scale

��

less units installed

more units installed

more units installed

3.2.4 Citizen Acceptance of the System

Empirical survey results on average citizen acceptance of specific energy technology

max Ordinal scale

��

small number of plants

as baseline more units installed in isolated areas

3.3 SOCIAL AND INDIVIDUAL RISKS

��


��



min YOLL/kWh

��

reduced risk due to reduced fluel consumption





min DALY/kWh

��


reduced rish due to reduced fluel consumption

reduced rish due to reduced fluel consumption

64



Explanation option1

Explanation option2

Explanation option3


min

��



min Fatalities/kWh

��

small systems on roof




��

3.3.3 Perceived Risks ��



min Ordinal scale

��



min Ordinal scale

��

3.3.4 Terrorist Threat ��

65



Explanation option1

Explanation option2

Explanation option3

3.3.4.1 Potential of attack Potential for a successful attack (RA)

min Ordinal scale

�� smaller area to survey

larger area to survey

larger area to survey

3.3.4.2 Effect of a successful attack

Likely potential effects of a successful attack (RA)

min Expected number of fatalities

��

no apprieciable differences



3.3.4.3 Proliferation Potential for misuse of technologies and substances within the energy chain

min Ordinal scale

��

few quantities potentially dangerous substance



3.4 QUALITY OF LIFE

��

3.4.1 Socially compatible development

��

3.4.1.1 Equitable life conditions

Share of the effective electricity costs in a social welfare receiver budget

min %

��

higher investment cost




max Factor

�� no apprieciable differences



3.4.2 Effects on the Quality of Landscape and Residential Area

��

66



Explanation option1

Explanation option2

Explanation option3

3.4.2.1 Effects on the quality of the landscape

Functional and aesthetical impact of energy infrastructure on landscape

min Ordinal scale

��

smaller area of the solar field

larger area due to the larger solar field

larger area due to the larger solar field

3.4.2.2 Noise exposure Number of residents feeling highly affected by noise caused by the energy facility or transports to and from the energy facility

min Ordinal scale

��




3.4.2.3 Contribution to traffic

Total traffic load (LCA mainly)

min to be determined

��

smaller plant, less O&M

larger plant, more O&M

larger plant, more O&M

�

�

67

6 Solar Thermal Power Plants �� !"��# ��

6.1 Technology credited in RS1a for 2025-2050 Of all the renewable technologies available for large-scale power production today and for the next few decades, CSP is one of a few with the potential to make major contributions of clean energy because of its relatively conventional technology and ease of scale-up. Solar thermal power plants can be designed for solar – only operation, to satisfy peak load demand, but ideally, by means of storage systems, they can achieve up to 100% of solar share and operated as conventional base load power plants. A number of solar thermal power units, with a total capacity 354 MWe, have been put in service since the early eighties in USA and up to 2007 they have produced more than half of the worldwide solar electricity. After a long period of interruption due to lack of incentives, in 2007 two new power plants in Nevada and Spain have been put in operation while the construction of other new plants has started in Spain and Algeria. Experts expect to see a relevant growth of the sector in the next years mainly due to the new installations in Spain and to the other initiatives under way in the world; as a result of this trend the target of 1,5 – 2,0 GWe of overall installed capacity will be reached around 2010. Thanks to research combined with experience gained in the existing plants, STP electricity has became more and more economical; the competition among different concepts and technologies will bring in a decade to further reduction of installation and O&M costs, making solar electricity competitive with other power resources. Thanks to the new legislations in Europe and North Africa a number of different technical options are today in discussion in such a way that the ultimate plant concept has to be still selected. Parabolic trough system using thermal oil is considered today the most proved and mature technology; it permits to realise power plants in the range of decades of MWe and probably few hundreds in the future. This concepts is now living a new development phase due to the necessity to couple the solar field with giant thermal storage systems capable to accumulate heat at high temperature and to permit the operation of the plant even at night. This necessity is not related to the technology itself but to the legislations in force (in Spain and Italy) that require that the electricity produced from STP plants has to be mainly solar while the fossil energy contribution has to limitated as minimal as possible. This approach will probably be maintained and extended in the future and thermal storage, increasing the annual hours of operation, will became indispensable to permit the economic viability of the plants under these regulations. Two important variants of the oil parabolic trough technology are the Direct Steam Generation parabolic trough and the Molten Salts parabolic trough. Both the concepts are under investigation in Spain and Italy and represent important evolutions of the parabolic trough concept. The success of these concepts under test can bring to a reduction of the generation cost. Main challenges for the DSG system are the possibility to regulate the steam production directly in the solar field under variable conditions of irradiation and to accumulate the heat of the steam in a storage system. For the Molten Salts system the challenge consists in the characterisitc of thermal fluid: from one side they facilitate the accumulation of thermal energy but on the other hand they have to be maintained always above 225 °C to remain liquid, in addition they become aggressive for steel above 560 °C.

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Power Tower system has been the first CSP concept to be developed in the early eighties. After a number of experiences with water-steam, it obtained a positive demonstration using molten salts as thermal fluid in the Solar Two power plant in Barstow California. This plant was equipped with a thermal storage working at high temperature based on two charge - discharge tanks and demonstrated the possibility to use molten salts as efficient primary fluid and thermal storage media. Nowadays new power tower plants using water - steam as working fluid have been put in operation in Spain as peak power plants while a new initiative for a relatively large power tower plant using molten salts is on the way. Main concerns on this concept are related to the practical possibility to realise plants of decades of megawatts because of the size of the tower, the weigh of the receiver and the focal length of the heliostats. On the other hand molten salts make feasible to realise huge thermal storages, up to 16 hours of operation equivalent, implying almost 6000 hours of service per year, that makes this kind of plant capable to guarantee the continuity of generation, which is one of the most appreciated characteristics in the power sector. On the contrary, water-steam system presents important difficulties to accumulate energy at high temperature at competitive cost and efficiency, and till today, only tactical storages have been tested for this concept. Despite of these obstacle some new projects propose the innovative multi tower concept that consists in to couple a parabolic trough field with a power tower field producing saturated steam at high enthalpy in the range of power of 50 –100 MWe. Fresnel linear collector or Fresnel troughs, even conceived in late 70s (Francia and others), have been successful tested in small experiences only in the last years (Mills, Solarmundo, and recently Ausra and Novatec). The experiences have been focused on the performance of the collectors and only recently these plants have been coupled with a dedicated steam cycle to generate electricity at small scale. From this point of view this technology is still at an early stage of demonstration. Nevertheless experts confide in its potentialities due to a simple technology and a reduced requirement of material and manpower. A reduction of efficiency in conversion of solar energy in electricity should be over compensated from a strong reduction of manufacturing costs. At the beginning, the ideal application of this concept seemed to be the integration with conventional power plants that have a medium pressure stage turbine capable to receive the solar steam produced by the Fresnel collector field. This scheme implies that solar energy represents just a contribution to the power generated from the conventional plant and, for this reason, the plant could not be recognized as solar thermal power plant from the feed-in laws around the world. Last developments shown that Fresnel collectors can be coupled with an autonomous power block to generate electricity. This scheme will have to be proved extensively before to assess the economical viability of this concept as its overall efficiency is lower than the parabolic trough system one. Nevertheless some announcements and initiatives in USA suggest that the deployment in large scale of this technology is just behind the corner. On the other hand it’s quite probable that in next future performances of Fresnel collectors will be improved to permit to drive standard Rankine steam cycles with high efficiency in solar only mode. The possibility to realise large, efficient thermal storages remains one of the main challenge for this technology, as far as the other concepts using the water – steam cycle; the solution of this problem can represent one of the breakthrough for a massive CSP deployment based on Fresnel collectors . Dish - Stirling concept has been developed in different phases trough a number of prototypes in the US and Europe over almost 30 years time. Despite of the relevant progress in reliability and efficiency, so far no relevant commercial o pre-commercial installation have been realized. Due to the small size of the generators, solar electricity produced by means of dispersed D-S generators is intrinsically more expensive than the electricity produced by large STP units; nevertheless, due to their high efficiency, 24% demonstrated on routine base, and the reduction of the component’s cost by means the industrial series production, the D-S kWhe can become competitive with the PV kWhe as far as small diesel generators. For this

69

reason, D-S technology has been retained, so far, suitable for distributed generation. In the last years though, large “solar farms” of hundreds of megawatts have been proposed in the United States. Lack of supply of research funds and dedicated feed – in tariffs seems to be the major obstacles to the development of this technology that suffered since the beginning of inconstant interest from stakeholders and public decision makers.

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table 9 Technical and economical characteristics of the STP technologies and their status of development. Technology

Typical operating temperature

Concentration ratio

Tracking

Net effic. a)

Type of

operation

Installed Capacity

2007

Annual output 2006

Currently projected

°C

%

MWel

GWhel

MWel

Parabolic trough

260- 400

80

One axis

14

commercial 419 988 1,100(Spain) 2,675(worldwi

de)

Fresnel

275 200 One axis

9 commercial 513

Central receiver

270-800 500 -1000 Two axis

13-18 commercial 10 46 Spain 566 worldwide

Dish Stirling 500 - 800 800 -2000 Two axis

15-24 demo 0,3 800 (USA)

a) defined as generated electricity / solar energy intercepted

In general terms the STP technologies present strong and weak points that can facilitate or slow down their deployment: The huge abundance of the primary source, solar energy, distributed in vast areas of the world, in countries different for social and political conditions, can contribute to reduce the political and economical pressure existing today around the conventional and nuclear sources and favorite a climate of positive relationships worldwide. From the technical point of view STP has the most appreciated quality to produce electricity taking in account the grid requirements thanks to the thermal storage systems or hybridisation. Energy storage permits to make stable the generation of solar electricity and to cover the peak time service as well as the base load service . STP technologies require the minimum specific surface of terrain per green kWhe produced. This aspect can be an important driver for its deployment also in developed country were land cost and fractionated property can add difficulties in settling plants. The main barrier to the diffusion of the STP technology is the generation cost which is lower than the PV generation one but still to high to compete with the conventional bulk generation. Research and industrial production will play a crucial role in reducing the solar thermal electricity cost. Thanks to the experiences accumulated in the existing plants, O&M cost has decreased significantly. At the same time 20 and more years of research have leaded to more efficient systems and components and accumulated a relevant mass of knowledge in design, component durability and reliability. Mass production of solar components is the other driver for a relevant reduction of the installation cost. As all the STP plants are realised assembling hundreds or thousands of identical pieces: efficient mass production and mounting methods are critical for the final installation cost. Because of their dimensions, collectors and heliostats are mounted directly on site; the size of the plants is another parameter that can influence the fabrication techniques as far as the vicinity of some plants in the same area. STP presents some industrial aspects one can find in PV, aeolic and biomass sectors, and

71

consequently its costs will be progressively reduced on the base of the figure of installations as happened to the other mentioned technologies. A part for Dish – Stirling systems, the tree other concepts, including their sub cases, share some common aspects:

a) a conventional power block and related civil infrastructures ( Rankine cycle, turbine, alternator, foundations, grid connections, service buildings etc.,); power block can range from 10 MWe up to hundreds of MWe in the future;

b) a solar field realized by hundreds or thousand of identical components assembled on site that take some square km of flat land requiring extended cabling, electronic supervision and systematic O&M

c) a thermal storage system ranging from few hours up to 16 or more hours of equivalent operation realized using various technologies depending on the nature of the primary fluid

d) a requirement of flat land, preferably or regular shape and an annual integral of direct normal insolation in the order of 2000 kWh/m² or more.

Each of these aspects contributes differently to the cost of solar electricity . The power block specific cost, for example, tents to decrease with size, and to stabilize in the range of 100 – 200 MWe, while its efficiency tents to improve. For these reasons the ideal size of each single plant should be in the range of few hundreds of MWe which could correspond to a land size in the range of 3-10 square km. It is likely that above this size the land availability becomes critics, even in under populated zones, and also that the total investment cost of a plant becomes difficult to handle, approaching the range of one billion of Euro, at today costs. The solar field and its components represent the main area of potential improvement both technological and economical. Improvement in efficiency and reliability, as already seen in the last 10 years, are very probable such as a reduction of costs due to large series fabrication and to new efficient methods of assembling materials on site. The thermal storage system represents the most critical area of development. Despite of the fact that a number of different storage systems have been investigated or tested during almost 30 years, so far only storages of small size have been realised and tested for quite short times. Nowadays only 3 concepts seems to be promising: the two charge - discharge tank system based on molten salts as thermal media, the concrete storage where heat is stored in a heavy concrete block crossed by tubes for the primary fluid and the change phase system which consists in transferring the solar heat to a fluid that changes its physical status absorbing the heat and releasing it when it returns to the previous form. The two molten salts tank concept is the unique large storage system that was tested successfully at significant scale and today is being applied at enlarged scale in the new parabolic trough Andasol 1 and 2 plants in construction in Spain. The success of this installation will give a new impulse to the parabolic trough system and to the STP in general. Finally the land requirement can represent an obstacle to the deployment of the STP, especially in South Europe, due to the cost of the land and the average small size of the properties. These two aspects, non techniological, can influence the total cost investment and the duration of negotiation and, in the end, the construction time. Increase of efficiency of the plants contributes to reduce the land requirement. Beyond these “internal” common aspects, the development of the STP will depend , like the other RES technologies¸ from a number of external factors due to the energy policies. In the RS 1A these factors are identified as follows:

72

a) Release of feed-in laws for STP b) Signature of power purchase agreements c) Reduction of subsidies for fossil and nuclear power plants d) Increase of fossil fuels prices e) Internalisations of the cost of CO2 reduction f) Application of the Clean Development Mechanism g) Research and development spending Combining the internal and external factors, assuming different degrees of positive evolution, tree different scenarios of development for the STP sector have been formulated in RS IA. Results of these evaluation are reported in the following table: table 10Installed capacity within the different technology development scenarios

In the report RS IA a Life Cycle Inventory for 5 different type of solar thermal power plants is reported. The plant type taken in consideration for the analysis are different versions of the tree main STP concepts: parabolic trough, power tower and Fresnel collectors. Tree types of storages have been also considered in the analysis: the two molten salts tanks system, the massive solid concrete system and the Phase Change Material system. Due to the mix of components, different size and efficiencies, it’s hard to get a unique synthetic result from the analysis. In general it can be seen that storage system plays a critical role in terms of material consumption. Comparisons among the storages are based on a number of assumptions because the solid concrete and the PCM systems have been realised only at experimental scale. The solid concrete storage system seems to be the most requiring in terms of material and cost, on the contrary the molten salts system is retained to be the less demanding in terms of LCI. Regarding the solar field, the Fresnel collectors system is retained to be much more cheaper respect to the others. Regarding the release of CO2 and other pollutants, the impact analysis shows that in general for all the plant – storage concepts you have a decreasing trend of emissions. For the two molten salts tanks system a relative emission of N2O has been indicated due to the slow degradation of the salt. Finally the land use increases with the solar share but, as the extension of the solar field is directly related to the electricity generated, the unitary land use increases of the order of 40% maximum respect a reference solution of STP plant operated in hybrid mode. To evaluate the sustainability performance of different technological options of STP plants, in view to the subsequent Multi Criteria Decision Analysis that will be carried out in the RS 2b task of the NEEDS Project, a number of plant concepts have been selected and compared with a reference baseline technology. The comparison has been performed applying the set of criteria and indicators defined in the RS 2b Report “Environmental, Economic and Social Criteria and Indicators for Sustainability Assessment of Energy Technologies” (Deliverable No. D 3.1 – RS 2b).

73

To simplify the comparison, tree different ideal reference plant schemes have been chosen over a large number of alternatives, taking in consideration the degree of development of the technologies and their probability to find application in the next coming years. The existing SEGS plants in California have been chosen as baseline technology assuming that this kind of scheme will remain the most economic and easy solution for bulk production of solar electricity if hybridisation with fossil source will be allowed. In the following a detailed description of the various options is listed: . Baseline technology: SEGS (Solar Electricity Generation System) power plant. This type of plant represents the beginning of the development of the technology of the parabolic trough using thermal oil as primary fluid. Nine of these plants, in different size and scheme, have been constructed during the eighties in California and operated continuously up today. SEGS plants are the practical demonstration that STP concept works and can satisfy the economic conditions of the market electricity. During many years of operation a lot of lessons have been learnt on this technology in such a way that today it can be considerate the most proven and reliable. Recent new projects in USA and in Europe have been inspired to this concept and adapted to match the requirements of local legal frameworks. The keys of the success of this system is the hybridisation with a conventional source, gas or heavy oil, in such a way that 75% of the production is due to the energy produced from the solar field and 25% via the fossil source. In this scheme no storage is needed and regulation of the plant is done to optimize the solar production and, at the same time, to guarantee at best the continuity of the production, especially during the peak hours. A number of factors, such as the abundance of solar energy in semi arid zones and the electricity market based on hourly tariffs, make quite probable the construction of new STP plants without storage. The new Nevada Solar One power plant, 64 MWe sized, without storage and even without hybridisation, is an example of this development line that tents to reduce the investment cost as much as possible. In case that a new feed – in tariff law would be released in the USA, admitting hybridisation, the SEGS concept will receive a further impulse. New solar components, improved during the last years on the base of the operation experience, will permit to reduce further the contribution of the fossil source, reducing as well the emission impact of this kind of plants.

figure 9Aerial view of five 30 MWe SEGS plants at Kramer Junction California. This complex is still nowaday the larger installation for prodution of solar electricity in the world.

74

For the need of the comparison of the sustainability performance an ideal 100 MWe SEGS plant, with oil heater for hybridisation fuelled by gas ( or heavy oil) has been considered. Due to the maximum working oil temperature of 394 °C and the cooling system based on air condenser the maximum efficiency of the Rankine cycle in solar only mode is 34%. . Option 1: Parabolic trough solar field using thermal oil as primary fluid coupled with a large thermal storage based on the molten salts tanks concept. . Option 2: Power tower plant coupled with a large thermal storage based on the molten salts tanks concept. . Option 3: Fresnel collectors power plant coupled with a large thermal storage based on the PCM phase change material. The following sections describe each of the tree alternative technological options mentioned above, as well as the main highlights that have come out from their comparison with the reference option on the basis of the set of criteria and indicators put forth by the RS 2b Report. Lastly, a full overview of the results of these comparisons and the reasons underlying them, is appended at the end of this chapter. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

No influence



6.2 Option 1: Thermal oil Parabolic trough system with molten salts thermal storage

6.2.1 Technology gap description This plant scheme is inspired to the new Andasol 1 plant under construction in Spain which is equipped with a “7,5 hours of operation” equivalent thermal storage. In this plant the solar field is coupled with a thermal storage realised by two large tanks containing molten salts in a temperature working range of 280 – 380 ° C. An oil – salt heat exchanger permits to charge or discharge the thermal energy between the oil and the molten salt. For the purposes of this job a plant of this kind with a nominal capacity in the range of 100 MWe and 16 hours equivalent storage is considered. With such a large storage the plant has a service profile of 6000 hours per year. The capacity of the plant should be double respect the Andasol one; this enlargement seems to be a quite easy reachable target at 2025. Due to the modularity of the solar field the construction of larger plants are also possible but assuming that these kind of plant will be settled preferably in south Europe, where land is expensive and fractioned in

75

relatively small properties, a capacity of 100 MWe could result a good compromise . Because of the storage and the base load service profile the solar field is 3 times larger than an equivalent SEGS plant without storage: the land occupation should be in the order of 6 km². As the maximum temperature of the primary fluid in about 400 °C the maximum efficiency of the Rankine cycle is assumed 33% net while the average annual overall efficiency is assumed to be 13%.

figure 10 - Aerial view of Andasol 1 50 MWe parabolic trough plant under construction in the province of Granada (source Estela Technology gap influence on criteria and indicators. Environment. The presence of a large storage implies the substitution of a relevant quantities of conventional fuel, gas or oil in hybrid generation, and in general in power generation. This spare of CO2 emission is just partially balanced from the increased amount of materials such as concrete, steel and glass required for the construction of the storage and the enlarged solar field. A valuable spare of row material is also obtained from the non construction of the auxiliary boiler in such a way that the final impact, in term of emission, is positive. Some emissions due to the degradation of the fluids utilized in the plant are just little increased because of the larger quantity of synthetic oil circulating in the solar field and the molten salts management. Requirement of land is 3 times larger then in a SEGS plant if related to the installed capacity, but, if it is compared on the base of the annual energy produced, it falls down to less than 2 times because the conventional production of a SEGS plant is substituted from the solar energy. On the other hand the impact on the wildlife is quite minimal especially in semi arid zones and the risk of contamination of soil is in general lower than for SEGS plants. Economics. Nowadays the investment cost for MWe of installed capacity and for annual MWhe produced are in general higher than for the SEGS plants. This is due to the increased mass of material for solar field and storage and land required. According to the scenarios elaborated in 12.2 RS Ia this situation should change quite rapidly because of strong reduction of the cost of solar component cost and of the power block in such a way that the electricity costs should be reduced progressively around 5 – 7 c�/kWhe at 2025 depending on the location of the plant and its duty profile. According to this

76

scenario it seems reasonable to consider that the Option 1 plants will become competitive with the SEGS plant after 2015. Social aspects. Main differences between the reference baseline technology and the Option 1 are the larger extension of land required, the increased number of jobs during construction and operation and the reduction of fossil fuel consumption. This last aspect can result in a better acceptance from the local community and to speed the settlement procedure. On the other hand a wider area to lease, or purchase, implies longer trade negotiation with the owners; in case the land is agricultural terrain some modifications in the local economy and habits can be implied. In South Europe, to gather areas of few square kilometers as a unique block, can often imply a modification of the local viability and local surface hydro system causing disturb and opposition among the inhabitants. Difficulties related to the land tent to increase with the surface extension mainly in Europe, while in USA, North Africa and other under populated areas, where land is often managed by public entities, you don’t expect to have more troubles.

6.3 Option 2: Power tower plant coupled with a large molten salts thermal storage

6.3.1 Technology gap description The reference plant for this option is a scaling up of the Solar Tres plant with a nominal capacity of 50 MWe and a thermal storage of 16 hours equivalent, that corresponds to a solar field tree times larger than a plant without storage. The land occupation should be in the range of 4 km² in circular shape. A size of 50 MWe with a unique tower seems to be a reasonable, reachable target at 2025, taking in account that plants in the order of 100 MWe have been just investigated in a feasibility study ( Eskom, South Africa), but never proposed so far. A number of open issues have to be solved before increase the size up to this figure, f.e. the weight of a giant receiver placed on top of a 200 m height tower is one of the main one; also the practical construction of heliostats with a focal length of 2000 m or more, with an aiming precision of 1/2000 rad, represents a real challenge. On the other end, the new project Solar Tres to be realised in Spain, which is based directly on the experience gained with Solar Two, has a nominal capacity of just 15 MWe. Also the other tower plants realised so far have 10 and 20 MWe nominal power while other projects, that integrate parabolic trough and power tower technologies in a unique plant, foreseen towers in same range of size. It is probable that a new generation of tower plants with nominal capacity of 50 MWe could born after a positive experience gained with the new plants recently constructed or under construction. Taking in consideration that over ten years passed between the Solar Two experience and the new installations, it seems reasonable that new plants, double sized, shouldn’t be in construction before 2015 – 2020 while a jump to a unique tower of 100 MWe, without intermediate steps, appears not probable even in the favorable case of positive results coming from the 10 – 20 MWe today plants.

77

figure 11 - Artist view of Solar Tres 15 MWe power tower plant project under development in the province of Seville (source Sener) Environment. As in the Option 1 the impact on the environment results reduced essentially because air pollution and CO2 emission are avoided as no hybridisation occurs. The absence of synthetic oil as primary thermal fluid also reduces the emissions of hazardous products, the risk of fire and soil contamination in case of severe accident. No impact on population and wildlife is expected in any case. Regarding the consume of row materials it has to be remembered that the tower construction and a larger number of heliostats require a relevant mass of concrete that can be regarded as a depletion of natural resources and an increase of green gases emissions. The requirement of materials for the auxiliary boiler, which is needed in SEGS plants, is reduced because just a small emergency salt heater if necessary. Even taking in account the impact due to the increased mass of materials required, the overall environmental comparison versus the SEGS plant is favorable to the power tower system. Economics. Power tower development suffers of the delay accumulated versus the parabolic trough system due to lack of interest during the second half of nineties. Its investment cost is intrinsically higher than an equivalent parabolic trough system because of the relevant civil works necessary for the tower. Its competitiveness with the parabolic trough can be obtained comparing plants with strategic storages, at sizes of few decades of MWe. Storage in power tower based on molten salts is intrinsically less expensive and cost effective than in any other concept and permits to gain competitiveness over the other technologies. As the maximum temperature of the primary fluid in about 550 °C, the maximum efficiency of the Rankine cycle is assumed to be 39% net, while the average annual overall efficiency is assumed to be 16% .

6.3.1.1 Social aspects. For this Option applies comments valid for the Option 1 as the most relevant differences with the baseline solution are the reduction of pollution due to the spare of fossil source and the enlarged area required for the plant. As the reference power plant is 50 MWe, the land area is just 1,5 time larger than the baseline SEGS case sized 100 MWe, 380 ha versus 202 ha (California), while the solar electricity production is about the same 260 GWhe/y versus 240 GWhe/y because of the larger number of operation hours. The tower represents a new element of difference that can create some opposition because of its

78

impact on the landscape. Once again these worries are mainly related to South Europe while they should be negligible in other under populated regions.

6.4 Option 3: Fresnel collector power plant coupled with a large thermal storage based on the phase change material.

6.4.1 Technology gap description The plant has a nominal capacity of 100 MWe and a thermal storage of 16 hours equivalent that corresponds to a solar field tree times larger than a plant without storage. The land occupation should be in the range of 4 km² because of the reduced request of land compared with the alternative parabolic trough concept. The maximum temperature of steam in the Rankine cycle is assumed to be in the range of 400 °C with a net efficiency of 33%. The storage system is based on the PCM concept that today seems to be the most appropriate for the DSG (Direct Steam Generation). This kind of storage is divided in tree different sections, each of them coupled with one of the section of the solar steam generation system. In the preheating section the energy is stored in a concrete block crossed by the feed water tubes, in the following section, named PCM module, a sodium nitrate mixture, that melts at 306°C, absorbs and releases the heat of the water steam fluid in the evaporation phase, and finally a third concrete block, crossed by the steam tubes, stores and releases the heat related to the superheating phase. Experience on this kind of storage is under way today and few operation data are available, nevertheless it is retained intrinsically more efficient and tailored for the DSG system than any other storage concept tested so far.

figure 12 Kimberlina California 5MWe Fresnel linear collector solar power plant under construction (source Ausra Environment. The spare of fossil energy corresponds to an environmental benefit as far as in the previous Options. The overall requirement of material for the Fresnel collectors and the PCM storage should be equivalent or inferior than in the other Options in such e way that

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comparison with the SEGS hybrid plants is even more positive. Like in the power tower solution there are no hazardous products that can poisoning soil or superficial water or to be realised outside the plants. Economics. The investment cost of this plant should result lower than the cost of the other options due the relevant reduction of the unitary cost of Fresnel collectors and the DSG system. The PCM storage increases the investment cost significantly, even more than the other storage systems, but in the end the overall specific investment of this kind of plant should be competitive with the other alternatives. LEC of solar kWhe should be slightly lower than the two other options but less than one expect at a first sight because Fresnel collectors have a lower efficiency and the possibility to reach 550 °C in steam superheating is today just hypothetical. For these reason the LEC of this technology should be in the range of 5 – 7 c�/kWhe at 2025. The reduction of investment cost represents an advantage above the other technologies in any case. Social aspect. Such as the previous Options, the social impact regards mainly the disturb created by the land occupation and the potential alteration of the local economy and habits. In South Europe the land use can be more impacting than the new job opportunities, while in semi arid zone in north Africa or in USA or in other under populated zone the new jobs can represent a positive drive for the settlement of the plants.

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6.5 Results of comparison of the tree technological options with the baseline SEGS assumed, in respect of the various criteria and relevant indicators.

Trend of indicators as compared to

the baseline technology Reasons for the trend

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7 Nuclear Technology

Franco Polidoro, CESI RICERCA, SSG Department

7.1 Technology credited in RS1a for 2025-2050 Given the energetic and environmental challenges facing our planet in the 21st century (doubling of energy requirements and increase in population by 3 billion before 2050 – see figure 13, increase fossil fuel costs and depletion of resources, fight against global warming), significant energy sources with limited greenhouse gas emissions are requested in the next decades. Nuclear energy can provide a significant contribution to meet these requirements, with long-term resource availability and the possibility to minimize radioactive waste. Nowadays approximately 450 nuclear reactors are in operation currently providing 17% of the world’s electricity, with limited gas emissions. Current reactors have demonstrated the maturity of the nuclear industry; the most recent and industrially available Generation III systems (e.g EPR) benefits from this maturity and produces further improvements in terms of operation, safety, cost saving.

figure 13 Scenario of energy growth for a sustainable future To provide adequate and sustainable electricity in the second half of this century, future prospects of cogeneration and the need for energy products other than electricity, such as hydrogen and high temperature heat for industrial processes, also induced a renewed interest in nuclear energy. The role of hydrogen as energy vector is of substituting hydrocarbons, whose resources are clearly limited. The other aspect that nuclear energy have to consider for the future is the optimal use of natural uranium resources and the necessity to minimize the waste. Even if the situation around the middle of the century does not lead to a shortage of uranium, because of additional reserves in phosphates or sea water, rising costs of recovery will lead to price increases. Continuing research and development on fuel and reactor technologies of Generation III systems are needed to optimise these evolving reactors, and to meet the energy needs of the 21st century. Improving to use up to 2% of the uranium energy content in Light Water Reactors (LWRs) is of special interest to temporarily mitigate the consequences of rising

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natural uranium costs, pending the deployment of fast neutron reactors in the second half of the 21st century. Fast neutron reactors breeder reactors with a closed fuel cycle should be able to use more efficiently the energy in natural uranium, reducing in addition the ultimate volumes of long-lived radioactive waste for disposal. Both the Generation IV International Forum (GIF), launched by the US-DOE in 2000, and the International Project on Innovative Nuclear Reactor (INPRO), launched by the IAEA in September 2000, have specified key technologies of new nuclear systems (known as Generation IV) :

�� Fast neutron systems with a closed fuel cycle for sustainable nuclear energy, i.e., efficiently using natural uranium (up to 80-90%, as opposed to 0.5% with LWRs today) and minimising quantities and decay heat of the ultimate disposable waste;

�� Advanced spent fuel treatment processes to optimise the nature of the ultimate waste and afford

increased resistance to proliferation risks;

�� High or very high temperature nuclear systems for energy applications other than electricity production such as hydrogen, process heat for industry, desalination.

Among the different fast reactors considered by the GIF, the nuclear systems able to give priority to closure of the fuel cycle, to support sustainability energy deployment and technologically oriented for nuclear hydrogen production, the most promising are the followings :

�� Sodium-cooled Fast Reactors (SFRs); �� Gas Fast Reactors (GFRs).

The SFRs take benefit from a long term experience feedback. However, sodium technology is heavy and expensive. Although no reactor of thus type has ever been built, GFRs appear a very attractive sustainable option, opening the door to high temperature application. For these nuclear systems significant developments are still needed in order to attain technical maturity allowing for industrial deployment. The first prototypes will probably be built towards 2020, but the effective deployment of 4th generation systems will probably take place towards 2030-2040. For that reasons it is likely that up to half of this century, Generation III systems will continue to supply nearly all the nuclear energy production. figure 14illustrates the transition from current reactors fleet in France to Generation IV technologies.

figure 14 Scenario of renewal of French nuclear plants

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An attempt at figuring out the evolution of nuclear technologies for the period 2025 – 2050, describing the possible development pathway, was made in NEEDS Project’s - Deliverable. 14.2, RS 1a “Final report on technical data, costs and life cycle inventories of nuclear power plants”. Prospective for 2025-2050 were made out from three different scenarios of worldwide deployment of nuclear technologies over the same period as reported in the table 11.

table 11 Pressurized Water Reactor of N4 type, EPR : European Pressurized Reactor, GEN IV : Nuclear Power Plant of the 4th generation, SFR : Sodium-cooled Fast Reactor

Scenario

Year 2000

Year 2025

Year 2050

Note

Pessimistic

N4

EPR

EPR

No Generation IV at all – evolutionary systems chosen for new plants in 2050

Realistic optimistic

N4

EPR

EPR +

GEN IV-SFR (few units)

Emergence of the Generation IV reactors that are the most known today with potential for industry maturity around 2040.

Very optimistic

N4

EPR

EPR +

GEN IV (50% fleet)

Emergence of very different concepts of Generation IV reactors, through an accelerated R&D process enabling them to be industrially mature before 2050

Legend - N4 :

The scenarios are defined as follows :

�� Pessimistic � Stagnation of nuclear energy worldwide: the uranium scarcity would not be a driver for the emergence of radically new technologies;

�� Realistically optimistic � Increase of nuclear energy to 1500 GW of installed capacity in 2050,

based on the WEC Scenarios B of the IIASA-WEC study. The dominant technology in 2050 will be Generation III reactors (e.g. EPR), with appearance of the first units of Generation IV reactors (at least first demonstrators). Among the Generation IV reactors, the Sodium-cooled Fast Reactor, should be ready for commercial deployment around 2040-2050;

�� Very optimistic � Increase to 2500 GW in 2050 based on the WEC Scenarios A of the IIASA-WEC study. In this scenarios with early deployment of fast reactors, the world nuclear fleet in 2050 could be composed of 50% of Generation III reactors like the EPR and 50% of fast breeder reactors.

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table 12 2 reports briefly some of the main technical figures that characterize the nuclear technologies as it was outlined by the RS 1a report. table 12 Main technical features of technologies considered for years 2000, 2025 and 2050

Parameter Unit PWR (N4 series)

EPR GEN IV (SFR)

Size MWe 1000 1590 1450 Life time Years 40 60 40 Enrichment process - Gaseous

diffusion Ultra-centrifugal Closed-reclycling of Pu

Due to the fact that the Generation IV reactors represent a technical breakthrough, with important technological changes not only in plant design but also for the entire fuel cycle, with implementation of important R&D programs, in 2050, nuclear energy generation is likely to be in a transition situation. The reactor fleet will be composed mainly by Generation III nuclear power plants, with appearance of new nuclear generation systems yet able to provide in addition heat and hydrogen. On the basis of these considerations, the realistic optimistic scenario has been considered as the reference one, in the present study. Moreover the technologies reported in the table 11(EPR + appearance of the first units of Generation IV reactors) has been taken as the baseline for evaluating the sensitivity, from the viewpoint of sustainability performance, of alternative technological options that can be envisaged for nuclear reactors in the period 2025 – 2050. The environmental, economic and social criteria and indicators considered for sustainability assessment of the energy technologies, are those defined by the Multi-Criteria Decision Analysis (MCDA) and reported within the RS 2b, Deliverable D 3.1, of the NEEDS Project. The technological options considered in this report can be then summarised as follows:

�� Baseline technologies: European Pressurized Reactor (EPR) up to 2025 and appearance of some units of Sodium-cooled Fast Reactor (SFR) within 2050.

�� Alternative option : European Pressurized Reactor (EPR) up to 2025 and appearance of Gas

Fast Reactor (GFR) for electricity and hydrogen production within 2050. The following section describes the alternative technological option mentioned above, as well as the main highlights that have come out from its comparison with the reference technology on the basis of the set of criteria and indicators considered in the RS 2b Report. The full overview of the results of these comparisons is provided in chapter 7.3. The degree of influence of a given option on each indicator has been represented in this table by an arrow as follows:

No influence



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7.2 Selected Option : Gas Fast Reactor

7.2.1 Technology gap description The GFR system is a fast-spectrum helium-cooled reactor with a close fuel cycle (see figure 15). Like thermal-spectrum helium-cooled reactors, the high outlet temperature of the helium coolant makes it possible to deliver electricity, hydrogen, or process heat with high conversion efficiency.

figure 15– Gas Fast reactor system description The GFR can use a direct-cycle helium turbine for electricity and process heat for thermo-chemical production of hydrogen. Through the combination of a fast-neutron spectrum and closed fuel cycle, GFR minimize the production of long-lived radioactive waste isotopes, thereby improving protection for the public health and environment. The GFR fast spectrum makes it possible to utilize available fissile and fertile material (including depleted uranium from enrichment plants) two orders of magnitude more efficiency than thermal spectrum gas reactor with once-through fuel cycle, so to meet the future requirements in terms of sustainable energy generation and effective fuel utilization. The GFR reference assumes an integrated, on-site spent fuel treatment and re-fabrication plant. A summary of typical design parameters for Generation IV GFR system is reported in table 3.

table 13 Typical design parameters for the GFR system

Reactor parameter Reference value Power Plant 600 to 3000 MWth Net plant efficiency (direct, Brayton cycle) > 45% Outlet coolant temperature (direct cycle) Up to 850 °C He pressure 5 - 7 MPa Specific power 50 - 100 MW/m3 Volumetric fraction Structures / He / Fuel 20 / 40 / 40 Fuel type Carbide / SiC

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7.2.2 Technology gap influence on criteria and indicators Environment Global warming potential. There is a wide international consensus that hydrogen offers considerable promise as a potential solution to the increasing demand of energy coupled with strong greenhouse gas reduction policies. The appearance in the nuclear fleet of Gas Fast Reactors, would have a positive impact on the climate changes, by reducing the production of greenhouse gases and depletion of non renewable fossil fuel resources. Impacts of air pollution on ecosystems. Lower impact than SFR (reference case) by reduction of greenhouse gases production. Waste. A Favourable impact on the environment could be expected by the lower amount of waste to be stored in geological repositories, being the inventory of material at high radiological impact efficiently recycled in GFRs. Economy Average generation cost. A high conversion efficiency, a simpler plant configuration and a construction cost potentially lower than the SFRs, should contribute to the reduction of the generation costs. Medium to long term independence from foreign import. The additional hydrogen production should contribute to the medium to long independence from foreign imports, increasing the energy autonomy and sustainability. Capital investment exposure. Construction cost potentially lower than SFR. Construction time. Potentially lower than SFR having a simpler plant design. Equivalent Availability Factor. Potentially lower than SFR being less proven technology. Social aspects Market concentration in the supply of primary sources of energy. The potential advantages of GFRs to meet the needs of energy products other than electricity, such as hydrogen and high temperature heat for industrial processes, should contribute to the development of different primary energy suppliers. Potential of energy system induced conflicts that may endanger the cohesion of societies. Potentially higher than SFR being a less proven technology. Willingness of citizen movements to act for or against realisation of an option. The potential advantages of GFRs to meet the needs of energy products other than electricity and the contribution to limit the use of fossil fuel resources, so reducing the global warming, would limit the potential for mobilization of public opinion to act against the realization of these nuclear systems. Empirical survey results on average citizen acceptance of specific energy technology. More easy acceptance of the nuclear system (see above). Expected Mortality due to severe accidents. Potentially lower than SFR having a simpler plant design and by the use of inert coolant Potential for a successful attack. Potentially lower than SFR where great amounts of sodium as coolant are used

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Share of the effective electricity costs in a social welfare receiver budget. Reduction of the generation costs (see above) Weighted index of work qualifications. Potentially higher work qualification for development of activities related to the hydrogen production and heat for industrial processes Functional and aesthetical impact of energy infrastructure on landscape. The hydrogen production, storage and distribution, would impact on the landscape of the entire infrastructures related to the generation technology chain.

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7.3 Results of comparison of the technological option with the baseline assumed, in respect of the various criteria and relevant indicators

CRITERION INDICATOR Direction of scale UNIT Indicator

trend Motivation

1 ENVIRONMENT 1.1 RESOURCES 1.1.1 Energy Resources

1.1.1.1 Fossil primary energy

Total consumption of fossil resources (LCIA)

min MJ/kWh Not applicable



min MJ/kWh �� Higher plant efficency

1.1.2 Mineral Resources (Ores)

Weighted total consumption of metallic ores (LCIA)

min kg(Sb-eq.)/kWh �� No differences

1.2 CLIMATE CHANGE

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trend Motivation

1.2.1

Global warming potential (LCIA)

min kg(CO2-eq.)/kWh ��

The hydrogen production contributes to limit the use of fossil fuel resources reducing the global warming.


1.3.1 Impacts from Normal Operation

1.3.1.1 Biodiversity (land use)

Impacts of land use on ecosystems (LCIA)

min PDF*m2*a/kWh �� No differences

1.3.1.2 Ecotoxicity

Impacts of toxic substances on ecosystems (LCIA)

min PDF*m2*a/kWh �� No differences



min PDF*m2*a/kWh �� see 1.2.1


1.3.2.1 Release of hydrocarbons

Large release of hydrocarbons (RA)

min t/kWh ��Not applicable

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trend Motivation

1.3.2.2 Land contamination

Catastrophic land contamination (RA)

min km2/kWh ��

1.4 WASTES ��



min kg/kWh ��Not applicable

1.4.2

Medium and High Level Radioactive Wastes to be stored in Geological Repositories

Total amount of medium and high level radioactive wastes to be stored in geological repositories (LCA)

min m3/kWh ��

Less amount of waste to be stored in geological repositories, being the inventory of material at high radiological impact efficiently recycled in GFRs

2 ECONOMY ��

2.1 IMPACTS ON CUSTOMERS ��

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trend Motivation


min �/MWh ��

Higher conversion efficiency, a simpler machine and a construction cost potentially lower than SFRs

2.2 IMPACTS ON OVERALL ECONOMY ��

2.2.1 Employment Direct jobs max Person-years/GWh ��

2.2.2 Autonomy of electricity generation

Medium to long term independence from foreign imports, based on domestic energy storage and/or resources

max Ordinal ��

The additional hydrogen production contributes to the medium to long independence from foreign imports increasing the energy autonomy and sustainability

2.3 IMPACTS ON UTILITY ��

2.3.1 Financial Risks ��

2.3.1.1 Capital investment exposure Total capital cost min � �� Construction cost

potentially low

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trend Motivation

2.3.1.2 Impact of fuel price changes Sensitivity to fuel price changes

min Factor ��

No influence. The yellowcake is a relatively small part of the overall cost, so changes on uranium price should have not impact on the operation of the utility


Construction time min Years �� Simpler plant design

2.3.2 Operation ��

2.3.2.1 “Merit order” for dispatch purposes

Total average variable cost or “dispatch cost”

min �cents/kWh �� see above

2.3.2.2 Flexibility of dispatch Composite indicator max Ordinal �� No influence


max Factor �� Less proven technology

3 SOCIAL ASPECTS ��

3.1 SECURITY/RELIABILITY OF ENERGY PROVISION ��


��

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trend Motivation



min Ordinal scale ��

The potential advantages of GFRs to meet the needs of energy products other than electricity, such as hydrogen and high temperature heat for industrial processes, contribute to the diversity of primary energy suppliers

3.1.1.2 Waste management

Probability that waste storage facilities will not be available

min Ordinal scale �� See 1.4.2

3.1.2 Flexibility and Adaptation

Ability to incorporate new technological developments and breakthroughs

max Ordinal scale �� No influence

3.2 POLITICAL STABILITY AND LEGITIMACY ��


Potential of energy system induced conflicts that

min Ordinal scale ��Less proven technology

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trend Motivation

may endanger the cohesion of societies

3.2.2 Willingness to act (Mobilization Potential)


Stakeholder dependent Ordinal scale ��

The potential advantages of GFRs to meet the needs of energy products other than electricity and the contribution to limit the use of fossile fuel resources reducing the global warming, could limit the potential for mobilization of public opinion to act against the realization of these nuclear system.



Stakeholder dependent Ordinal scale �� No influence

3.2.4 Citizen Acceptance of the System

Empirical survey results on average citizen

max Ordinal scale ��See 3.2.2

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trend Motivation

acceptance of specific energy technology

3.3 SOCIAL AND INDIVIDUAL RISKS ��


��



min YOLL/kWh �� No influence



min DALY/kWh �� No influence

3.3.2 Expert-based Risk Estimates for accidents min ��



min Fatalities/kWh �� Simpler plant design and use of inert coolant



min Fatalities/accident �� see 3.3.2.1

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trend Motivation

3.3.3 Perceived Risks ��



min Ordinal scale �� See 3.3.2.1



min Ordinal scale �� See 3.3.2.1

3.3.4 Terrorist Threat

3.3.4.1 Potential of attack Potential for a successful attack (RA)

min Ordinal scale �� Potentially lower than SFR where great amounts of sodium as coolant are used

3.3.4.2 Effect of a successful attack

Likely potential effects of a successful attack (RA)

min Expected number of fatalities �� No influence

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trend Motivation

3.3.4.3 Proliferation

Potential for misuse of technologies and substances within the energy chain


No influence. The GFRs meet the proliferation resistance and physical protection requirements established by GEN IV International Forum

3.4 QUALITY OF LIFE ��

3.4.1 Socially compatible development ��

3.4.1.1 Equitable life conditions

Share of the effective electricity costs in a social welfare receiver budget

min % �� Reduction of the generation costs. See 2.1.1


max Factor ��

Potentially higher work qualification for development of activities related to the hydrogen production and heat for industrial processes

3.4.2 Effects on the Quality of Landscape and Residential ��

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trend Motivation

Area

3.4.2.1 Effects on the quality of the landscape

Functional and aesthetical impact of energy infrastructure on landscape


The hydrogen production, storage and distribution, would impact on the landscape of the entire infrastructures related to the generation technology chain.

3.4.2.2 Noise exposure

Number of residents feeling highly affected by noise caused by the energy facility or transports to and from the energy facility

min Ordinal scale ��See 3.4.2.1

3.4.2.3 Contribution to traffic Total traffic load (LCA mainly)

min to be determined �� No influence

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7.4 References [1] Energy to 2050 – Scenario for a Sustainable Future – International Energy Agency

(IEA/OECD) Paris, France, 2007. [2] A role of nuclear power in Europe – World Energy Council, 2007 [3] Gas-cooled nuclear reactors – A Monograph of the Nuclear Energy Directorate,

CEA, 2006 [4] A Technology Roadmap for Generation IV Nuclear Energy Systems – GIF-002-02, 2002 [5] Global Energy Perspectives – International Institute for Applied Systems Analysis (IIASA)

and World Energy Council (WEC), 2001 [6] R&D Strategy in France: The Gen IV initiative and the studies on Innovative Fast Nuclear

Systems - CEA/Nuclear Energy Division, 2006 [7] A comparative analysis of SFR and GFR, CEA/ Nuclear Energy Division

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