floating solar chimney technologyfinal

Solar-Aero Electric power plant with Floating Solar Chimney

1. ABSTRACTThis is an energy and global economy transient period. The end of Fossil fuels (oil and natural gas) is not too far. Climate change indications due to global warming threat are accelerating. Climate change policies should be agreed upon and urgent measures should be taken. Global warming due to greenhouse gases emissions (CO2, CH4 etc.) is a reality scientifically documented. For an estimated average cost of 20-30 EURO/tCO2, the carbon emissions cost in Greece for the minimum projected fossil fueled electricity of 50000 GWh/year, even for a 50% to 50% share between coal and natural gas, it will reach 750-1000 million EURO per year after 2012. Thus for Greek electricity producers ( etc.) the Kyoto protocol penalty cost is very heavy. Floating Solar Chimney (FSC) technology is a low cost version of solar chimney technology. The power plants of the FSC technology do not demand water, operate continuously (24X365) and their average daily electricity production is proportional to the daily horizontal irradiation. A large scale application of the FSC technology in Greece, or in MENA area for Greece, is feasible and can be implemented in a few years. Applying this cost efficient solar technology as well as other renewable technologies, Greece can fulfill its Kyoto protocol obligations and its CO2 emissions cost could be minimized.

2. THE CO2 EMISSIONS COST FOR FOSSIL FUELED POWER PLANTSThe energy sector is the major contributor of the green house gases due to fossil fuelled technologies in electricity generation, transport, industry etc. For year 2010 an estimated quantity of 29,000 Mt of carbon dioxide will be spread to the environment by fossil fuels of which: 36.4 % for electricity generation 20.8 % for the industry 18.8 % for transport and 14.2 % for household, service and agriculture and 9.8 % in international bunkers

The mechanism of Kyoto protocol aims to make objective the external cost at least for the threatening carbon dioxide (CO2) emissions through trading their rights. The cost of the emitted CO2, sooner or later it will reach at prices 20-30 EURO per ton of CO2 and after the year 2012 the fossil fuelled PPs should pay for every ton of CO2 emitted by them. Taking into consideration that 1 Kg of coal has a thermal energy of ~8.14 KWh, thus a modern coal fired power plant with efficiency ~45% will generate by this ~ 3.66 KWh and will emitt to the environment 3.667 Kg of CO2. Thus in a modern coal fired plant approximately 1.0 Kg of CO2 is emitted per generated KWh. For the existing in Greece


lignite coal fired power plants this figure is 50% higher and for modern combined cycle natural gas power plants could be 50% smaller. Thus for an estimated average cost of 20-30 EURO/tCO2, the carbon emissions cost, after the year 2012, for the minimum projected fossil fueled electricity generated in Greece of 50000 GWh/year, and for a 50% to 50% share between coal and natural gas, will reach the amount of 750-1000 million EURO per year. In case of CO2 prices rise to 50 EURO/ton, the carbon emissions cost for Greek electricity generating companies it will be extremely heavy even beyond 2 billion EURO/year. In this case the electricity tariffs for the consumers could be increased by 50% only for carbon emissions penalties. Thus urgent measures by the Greek state and electricity producers are necessary. The investments in renewable electricity technologies should be encouraged and should be increased, however with the existing status of technology the wind and solar technologies without storage systems can enter to the electric grid up to 20 % of the power of the system. Taking into consideration a projected maximum power demand of 12 GW for the Greek electricity system, the maximum power by all renewable producers can not be more than 2.2 GW. For an estimated maximum annual production (by wind turbines) of 2500 KWh per KW, the annual energy offer to the Greek electric grid will not be more than 5.5 TWh, that is approximately 10% of the projected fossil fueled generated electricity. Thus the decision for the investment increase in classic renewable technologies is necessary but not enough. The other two options are the nuclear power plants and the coal fired power plants with carbon capture and storage. Even if the decisions for such technologies could be magically supported by the majority of the political parties, the public opinion and the local communities in the places of their installation, due to complicated technological and legal matters that should arise, their implementation it could last decades beyond the year 2012. Thus another approach is necessary. My proposal is related to a low cost alternative of solar updraft tower technology named Floating Solar Chimney technology.


3. Floating Solar Chimney TechnologyA cost competitive solar technology that can secure worlds energy demand and eliminate the global warming threat

IntroductionSolar chimney electricity generation power plants are referred to as solar updraft towers and the related solar chimneys are huge reinforced concrete structures. However due to the high construction cost of the concrete solar chimneys the solar up-draft tower technology is expensive demanding a high initial investment in comparison to its competitive solar technologies. Their solar up-draft towers are huge structures of high initial investment cost that can not be split into small units. That is possible for the relatively also expensive PV solar technology. Floating solar chimney (FSC) technology, is a low cost alternative of the solar updraft towers. The FSC technology is the advisable one for candidacy for large scale solar electricity generation especially in desert or semi desert areas of our planet and a major technology for the global warming elimination. The Floating Solar Chimney Power Plant, named by the author as Solar Aero-Electric Power Plant (SAEP) due to its similarity to the Hydro-Electric power plant, is a set of three major components:

The Solar Collector (greenhouse) It is a large greenhouse open at its periphery with a transparent roof supported a few meters above the ground. A low cost alternative (patent pending) is described in chapter 4.


The Floating Solar Chimney (FSC). It is a tall fabric cylinder placed at the centre of the solar collector through which the warm air of the greenhouse, due to its relative buoyancy to the ambient air, is updrafting. Floating Solar Chimney is patented by the author in USA and several other countries. The Electric Power Unit. It is a set of air turbines geared to appropriate electric generators in the path of updrafting warm air flow that are forced to rotate generating electricity. The gear boxes are adjusting the rotation speed of the air turbines to the generator rotation speed defined by the grid frequency and their pole pairs.

The energy source, for the rotation of the air turbines and the electricity generation, is the horizontal solar irradiation passing through the transparent roof of the greenhouse and heating the ground beneath it. The ground thermal energy is partly transferred to the air stream, entering the greenhouse and moving towards the FSC bottom entrance. The up-drafting air mass through the FSC, due to its relative buoyancy to the ambient air, is offering a part of its thermodynamic energy to the air turbines rotating the geared electric generators, which generate electricity. Thus the first two components of the floating solar chimney power plants form a huge thermodynamic device, up-drafting the ground ambient air towards the upper atmosphere layers and the third component is the electricity generating device operating by the up-drafting warm air mass. Due to ground thermal storage capacity the electricity generation of the SAEPs is continuous and uninterrupted.


4. FUNCTIONAL PRINCIPLE:The principle is shown in fig below, Air is heated by solar radiation under a low circular translucent roof open at the periphery; the natural ground below it form an air collector. In the middle of the roof and the natural ground below it form an air collector. In the middle of the roof is a vertical tower with large air inlets at its base. The joint between the roof and the tower base is airtight. As hot air is lighter than cold air it rises up the tower. Suction from the tower then draws in more hot air from the collector, and cold air comes in from the outer perimeter. Continuous 24 hours-operation can be achieved by placing tight water filled tubes or bags under the roof. The water heats up during day time and releases its heat at night. These tubes are filled only at once, no further water is needed. Thus solar radiation causes a constant updraft in the tower. The energy contained in the updraft is converted into mechanical energy by pressure-staged turbines at the base of the tower, and into electrical energy by conventional generator.


5. CONSTRUCTION: Floating solar chimney:In order to increase the efficiencies of the solar chimney power stations we need solar chimneys of even higher heights. The forces acting on he FSC are basically two: The sub-pressure forces. The forces, which are resulted from the static pressure difference between the warm stream of air inside the FSC and the air on its exterior. The forces from the external winds, which are appeared at the places where the FSC is installed. The FSC construction is made by a series of balloon-rings from light enduring (airship) fabric connected successively in such a way that they form the main cylinder of the solar chimney. if necessary, special supporting rings placed between the balloon rings (see figure 2). These rings have negligible thickness and diameters smaller or equal than the diameters of the lifting balloons.

Fig.02 To encounter external winds forces is a rather more complicated issue. To do so the supporting rings are not sufficient, although they do help in this respect. The external winds problem is encountered by the FSCs deflecting ability.


Thus when external winds appear the FSC is deflecting, reaching its angle of balance (figure 3 and 4). In this way, in its balance position, the FSC encounters vertically only the drag forces from the velocitys normal components, which are counter-balanced from the opposite FSCs buoyancy components. These normal forces to the FSCs cylinder are encountered locally with the assistance of the supporting rings. Wind velocitys tangent component creates a friction force parallel to the FSCs cylinder without deforming its shape. As already stated in order to encounter the winds action on the FSC, it should have a deflecting ability. For this purpose two more elements are necessary: A system that will keep the FSC at its position and which will receive the parallel and tangent forces from the external winds. This system is a two-part heavy base, which can incline on the FSCs seat without parting from it. (Figure 4). A flexible (accordion type) folding part of its base which will be unfolded partly as a result of the deflection, preventing the warm air to escape by the bottom of the structure (figure 4).

Fig.03

Fig.04

This winds velocity variation creates differential forces along the chimneys cylinder. To encounter these differential forces the chimneys cylinder is separated in parts. These parts are constructed by a fixed number of tube balloon-rings. The parts are separated by isolation tubes filled with environments air, which can easily get in and out of them.


These relief tubes isolate dynamically the consecutive parts of FSC from each other, allowing each part to reach its own deflecting angle, depending on the average wind velocity on the altitude where it is located.

Fig.05

A computer animation for a part of a FSC is shown in fig. (05). The strength and thus the weight of the supporting rings are defining the dimensions of the lifting balloon tubes. The existing modern plastic and composite fabrics and fibers, tested already to air ship and balloon industry have given valuable information and know-how for an appropriate construction of the FSCs, in order to resist to external strong winds .


The Floating Solar Chimney (A low cost fabric structure).In order to decrease the construction cost of the Solar Aero-Electric Power Plants (SAEPs) the inventor proposed to replace the concrete solar chimneys with lighter than air inflated fabric structures named Floating Solar Chimneys (FSCs). He is granted USA, AUSTRALIA, EU, CHINA, INDIA and SOUTH AFRICA patents for his invention. In a series of papers the inventor gave the main characteristics of the SAEPs with Floating Solar Chimneys. Low cost Floating Solar Chimneys up to 500 m with internal diameters 32 m 42 m, can be constructed with existing polyester fabric, giving to their respective Solar Aero-Electric Power Plants, low investment costs. By this innovating Floating Solar Chimney Technology for FSC heights of maximum 500m, up to 0.6 % of the arriving horizontal solar radiation on the solar collector surface, can be converted to electricity. An indicative representation of the small part of a Floating Solar Chimney main cylindrical air up-drafting body is shown in the lower figure. The inner core can be placed outside the fabric structure in order to protect by solar UV radiation the supporting and lifting balloons.


Solar collector (The Greenhouse):The FSCPS power output is proportional to collector area and tower height, i.e. proportional to the cylinder in fig.06.

Hot air from the solar tower is produced by the green house effect in a simple air collector consisting of a glass or plastic film glazing stretched horizontally two to six meters above the ground. The height of the glazing increases adjacent to the tower base, so that the air is diverted to vertical movement with minimum friction loss. This glazing admits the solar radiation component and retains long-wave re-radiation from the heated ground. Thus the ground under the roof heats up and transfers its heat to the air flowing radially above it from the outside to the tower.

Fig.07 The area under the roof is used for agricultural purpose, so that large area invested for FSCPS is not gated wasted.


Storage:If additional thermal storage capacity is desire, water filled black tubes are laid down side by side on the radiation absorbing soil under the collector. The tubes are filled with water once and remain closed thereafter, so that no evaporation can take place. Since even at low water velocities from natural convection in the tubes the heat transfer between ground surface and the soil layer underneath, and since the heat capacity of water (4.2 kJ/kg) is much higher than that of soil (0.75-0.85 kJ/kg) the water insides the tubes stores a part of the solar heat and releases it during the night, when the air in the collector cools down. This enables the plant to run for 24th per day on pure solar energy.

Fig.08


6. History

The Solar Chimney technology for electricity generation was inspired by several engineers in the first decades of 20th century. In 1926 Prof Engineer Bernard Dubos proposed to the French Academy of Sciences the construction of a Solar Aero-Electric Power Plant in North Africa with its solar chimney on the slope of the high height mountain.

Figure and data from the book: Engineers Dream By: Willy Ley, Viking Press 1954

More recently Schaich, Bergerman and Partners, under the direction of Prof. Dr. Ing. Jorg Schlaigh, built an operating model of a SAEP in 1982 in Manzaranes (Spain), which was funded by the German Government. This solar chimney power plant, of rating power 50 KW, was operated successfully for approximately 8 years . Its solar chimney was made by steel tubes of 10 m diameter and had a height of 195 m.. During its operation optimization data was collected. Prof. Jorg Schlaigh in 1996 published a book (titled The Solar Chimney) presenting the solar chimney technology.


A view of the Manzanares Solar Chimney Power Plant

The collected operational data were in accordance with the theoretical results. Prof. J. Schlaigh proposed in his book huge reinforced concrete solar chimneys of heights 500m-1000m. These solar chimneys are very expensive constructions. Therefore the investment cost per produced KWh on the solar chimney technology with concrete chimneys is higher than the competitive solar thermal technologies (SCP for example). However the solar chimney technology has an important benefit in comparison to the other renewable technologies (Wind, SCP, PV). This is the ability of its Power Plants, equipped with thermal storage facilities of negligible cost, to produce electricity for 24h/day, 365days/year.


7. The desert solar collector (A low cost greenhouse)The solar collectors of updraft concrete solar towers are ordinary circular greenhouses usually with double glazing transparent roofs supported a few meters above the ground. The periphery of the circular greenhouse should be open to the ambient air. The outer height of the greenhouse should be at least 2 meters tall in order to permit the entrance of maintenance personnel inside the greenhouse. The height of the solar collector should be increased as we approach its centre where the FSC is placed. As a general rule the height of the transparent roof should be inversely proportional to the local diameter of the circular solar collector in order to keep relatively constant the moving air speed. The circular greenhouse periphery open surface can be equal or bigger than the FSC cut area. These greenhouses are expensive and demand an expensive and continuous maintenance especially when will be installed in desert areas for cleaning their roofs. In desert application of the FSC technology the solar collectors will be used exclusively for air warming. Also in desert or semi desert areas the dust on top of the transparent roofs of the conventional greenhouses could be a major problem. The dust can deteriorate the transparency of the upper glazing and furthermore can add unpredictable weight burden on the roof structure. The cleaning of the roof with water or air is a difficult task that can eliminate the desert potential of the FSC technology. Furthermore in desert or semi-desert areas the construction cost of the conventional solar collector (a conventional greenhouse) could be unpredictably expensive due to the unfavourable working conditions on desert sites.For all above reasons another patented design (Patent under pending) of the solar collectors has been proposed by Prof. C. Papageorgiou. The proposed desert solar collector is a low cost alternative solar collector of the circular or rectangular conventional greenhouse which can minimize the works of its construction and maintenance cost on site. The solar collector is the unit of the SAEP used just to warm the ground beneath it and the moving air mass through it. Thus in deserts it is possible not to have the usual form of conventional greenhouses because no farming activity takes place beneath it. The modular solar collector shape is orthogonal, just like the usual shapes of the land fields. We can also use and follow the ground elevation on site, and put the FSC on the upper part of the land-field therefore the works on site for initial land preparation will be minimized. The greenhouse will be constructed as a set of parallel reverse-V transparent tunnels made of crystal clear double glazing as shown in the next figure. The height of the air tunnel should be 180cm in order to facilitate the necessary works inside the tunnel. All the parallel series of reverse-V tunnels of panels will slowly elevate, following the ground physical inclination and heading their warm air moving mass, towards a closed corridor of appropriate dimensions leading to the entrance of the FSC.


An indicative figure of a greenhouse made of several air tunnels is shown in next figure. Among the parallel air tunnels it is advisable that room should be made for a corridor of 40-50cm of width for maintenance purposes.


By above description it is evident that the desert solar collector is a low cost alternative of a conventional circular greenhouse for the FSC technology in desert or semidesert areas that minimize the works on site and lower the construction costs of the solar collector and its SAEP. Furthermore the dust problem is not in existence because the dust slips down on the inclined triangular glass panels. The average annual efficiency of the modular solar collector made by a series of triangular warming air tunnels with double glazing transparent roofs is estimated to be even higher than 50%. Thus its annual efficiency will follow the usual diagram of efficiency (or it will be even higher). The total cut area of all the triangular air tunnels should be approximately equal to the cut area of the FSC for constant air speed. The central air collecting corridor cut should also follow the constant air speed rule for optimum operation and minimum construction cost.


8. Direct production cost of MWh and investment costThe following table gives us the average direct production cost of MWh and the necessary investment per produced MWh among the most significant electricity generation technologies (for new investments). Fuel or Method of Electricity Generation Coal fired (not including carbon emission penalties) Coal fired with CCS (Carbon capture and storage) Natural Gas fired(not including carbon emission penalties) Nuclear Fission Wind parks onshore Wind parks offshore Concentrating Solar CSP Photo Voltaic PV Solar Up-draft Tower (concrete solar chimney) Floating Solar Chimney Biomass Geothermal MWh Direct Production Cost in EURO 55-60 Investment in EURO per produced MWh/year 200 Mode of operation and Capacity factor Combined cycle base load 85% Combined cycle base load 85% Combined cycle 85%

80-100

300-400

60-65

150

65-75 65 75 180

400450 500 650 2000

280 155

3000 ~2000

Base load 95% Intermittent 30% Intermittent 30% Continuous with thermal storage 30% Intermittent 15-17% Continuous ~50%

Less than 60 60-75 60-70

Less than 500 500-700 500-800

Continuous ~50%

Continuous 85% Continuous 90% (limited resource) Hydroelectric 60-65 500800 Continuous (load following, limited resource) From the above table it is evident that, for new investments, for renewable electricity generating technologies, the Floating Solar Chimney technology combines the continuous operation and the smaller capital expenditure per produced MWh/year. Also because the FSC technology does not demand any fuel its MWh direct production cost is equal to the lower investment, base load fuel consuming technologies (coal, natural gas, etc.), and the most important is that the SAEPs do not emit any greenhouse gases.


9. Principles of operation of the solar chimney technologyA floating solar chimney power plant (SAEP) is made of three major components: A large solar collector, usually circular, which is made of a transparent roof supported a few meters above the ground (the greenhouse). The transparent roof can be made of glass or crystal clear plastic. A second cover made of thin crystal clear plastic is suggested to be hanged just underneath the roof in order to increase its thermal efficiency. The periphery of the solar collector is open in order that the ambient air can move freely into it. A tall fabric free standing lighter than air cylinder (the floating solar chimney) placed in the center of the greenhouse which is up drafting the warm air of the greenhouse, due to its buoyancy, to the upper atmospheric layers. A set of air turbines geared to appropriate electric generators (the turbo generators), placed with a horizontal axis in a circular path around the base of the FSC or with a vertical axis inside the entrance of the solar chimney. The air turbines are caged and can be just a rotor with several blades or a two stage machine (i.e. with a set of inlet guiding vanes and a rotor of several blades). The gear boxes are adjusting the rotation frequency of the air turbines to the electric generator rotation frequency defined by the grid frequency and the electric generator pole pairs. The horizontal solar irradiation passing through the transparent roof of the solar collector is heating the ground beneath it. The air beneath the solar collector is becoming warm through a heat transfer process from the ground area to the air. This heat transfer is increased due to the greenhouse effect of the transparent roof. This warm air becomes lighter than the ambient air. The buoyancy of the warm air is forcing the warm air to escape through the solar chimney. As the warm air is up drafting through the chimney, fresh ambient air is entering from the open periphery of the greenhouse. This fresh air becomes gradually warm, while moving towards the bottom of the solar chimney, and it is also up-drafting. Thus a large quantity of air mass is continuously circulating from ground to the upper layers of the atmosphere. This circulating air mass flow is offering a part of its thermodynamic energy to the air turbines which rotate and force the geared electric generators also to rotate. Thus the rotational mechanical power of the air turbines is transformed to electrical power.


Solar Aero-Electric power plant daily operation due to thermal storage effectSAEPP of 4MW ,DD=1000m,H=700m,d=34m,Wy=1750KW/m2 180 160

produced power % and solar irradiation %

140 120 100 80 60 40 20 0

ground only plus tubes

0

5

10 15 solar time in hours

20

Ground only (blue), Ground plus artificial thermal storage (green), Solar irradiance % (red)

Efficiency as function of the solar chimney heightSAEPP of 4sqKm solar collector in a place of annual solar irradiation 1750KW/sqm 2.5

2

efficiency %

1.5

1

0.5

0 400

600 800 1000 1200 1400 1600 1800 2000 variable height of Floating Solar Chimney in m of internal diameter 60m


10.Similarity to hydro-electric power plantsThe Floating Solar Chimney power plants, due to their similarity to hydro-electric power plants, are named by the author Solar Aero Electric Power Plants (SAEPs). Their similarity is due to the following facts: The hydro-electric PPs operate due to falling water gravity, while the solar aeroelectric PPs operate due to the up-drafting warm air buoyancy. The electricity generation units of hydro-electric PPs are water turbines engaged to electric generators while the generation units of solar aero-electric PPs are air turbines engaged to electric generators. The energy produced by the hydro-electric PPs is proportional to the falling water height, while the energy produced by the solar aero-electric PPs is proportional to updrafting height of warm air, which is equal to the height of the solar chimneys. That is why Prof J. Sclaigh in his book named the solar chimney technology power plants as the hydro-electric power plants of deserts.

11.Continuous operationAs it will be shown later the SAEPs operate continuously due to the ground thermal storage. The minimum electric power is generated when the sun is just starting rising, while the maximum electric power is achieved about 2 hours after the suns maximum irradiation on ground. The power generation profile can become smoother if we increase the solar collector thermal capacity. This can be done by putting on its ground area closed tubes filled with water (as happens already in conventional greenhouses)

12.External wind effectsThe effect of external winds on the FSC can be encountered by the deflection of the FSC. The local wind pressure on the FSCs walls related to this deflection is limited in comparison to the operational sub pressure acting on the FSC walls. However the deflection of the FSC due to external winds is decreasing the operating height of the FSC. Hence in favorite places for STPSsinstallation the average annual speeds of local winds should not exceed for example 3m/sec and the weibull constant of the local winds is better to exceed 1.5. For such locations for STPS the operating height of the FSC is not more than 5% smaller, compared to initial height of 3000m. The intermediate, open to the environmental air, balloon rings can help the FSC to encounter the dynamic effects between the successive parts of the FSC, due to the differential forces by the variation of wind speed with altitude.


13.Air turbines and GeneratorsThe basic unit that transforms the dynamic energy of moving air into electric energy is the axial air turbine. In large power STPS there will be one or several air turbines always ducted. These air turbines transform the dynamic energy of moving air with constant speed, using the pressure drop, in rotating mechanical energy and finally through a gear box and an electric generator of the same power, into electric energy. The electric generator can be synchronous or induction depending on the use of the output electric power. However for a straightforward production of H2, with an electrolysis method, an appropriate generator should be designed. The air turbines of STPS, as already mentioned are of constant speed and stepped pressure. The usual wind turbines on the contrary are of constant pressure and stepped air speed. The wind turbines are designed and constructed to operate under severe external conditions and their power output is limited by the betz limit. Hence for the same diameter with a stepped pressure air turbine they produce much less power and are more expensive. The choice of the position, the number and the dimensions of the air turbo generators it is an important decision procedure but it cannot be examined in depth in the present paper.


14.Comparison with other Electric power station:The FSCPSs are assumed installed in places with annual solar irradiation ~2300 KWh/m2. For these places the FSCPSs construction cost will be in average in the range of 850 USD/KW (700 ).As FSCs technology experience for material and construction will be accumulated, estimate that a 15 % decrease in 2005 prices is reasonable to be expected. This means that in next to years the cost could be as low as 700 USD/KW (600 ). The operation and maintenance cost for FSCPSs is very small in comparison to any other system of power production. The only substantial maintenance expense is the renewal cost for Helium or NH3 escapes. It is estimated that a compromise between the purchase cost of fabric for lifting tubes, and its impermeability to the lifting gas, could limit the escapes to less than 10% per year. A prototype helium filled airship made by Koch Membranen GmbH&Co, had a 1%

helium escapes per year. Thus maintenance and operation cost for FSCPSs should be less than 1.5% of their construction cost. In order to compare FSCPSs with other non renewable power stations, we should take into consideration that all the fossil fuel power stations in average can operate easily above 6000 hour per year, thus they can produce in average the double output energy for the same power rating with the FSCPSs. However their maintenance and operation cost due to the fuel consumption is far more expensive in relation to FSCPSs costs. In the following table a rough comparison of FSCPSs with conventional power stations is given.


WETO World Energy Technology & climate policy Outlook 2030 dataPower Station Investment Cost in /kW Fuel Cost Year 2000 Gas Combined Cycle 745 Year 2010 587 Above Average Average Above Average Above Average Above Average Above Average Low Low Very Low Maintenance Cost

Coal Supercritical

1970

1303

Average

Coal Gasification

2631

1805

Average

Nuclear

3632

3574

Above Average

Biomass

2368

2198

Above Average

Wind Photo Voltaic

996 6457

911 4378 300-500

Zero Zero Zero

Floating Solar Chimney 350-580 (y 2005)


15.Future Scope1) Hydrogen Production:Doubly Fed Induction Generators(DFIG) or Synchronous generators (SG) should be used appropriately controlled in order to supply a constant voltage output that is necessary for the electrolysis production units. Their frequency variation does not have any effect on the electrolysis procedure because between the AC electric generators and the electrolysiss unit, an AC to DC converter is inserted, accompanied by an appropriate transformer. The supplied DC current to the electrolysis units is producing proportional quantities of Hydrogen, and oxygen as a by-product. Theoretically for electrolysis taking place in an environment of 25oC and Po=101.300 Pa, 2gr H2 (1 moll) and 16 gr O (0.5 moll) can be produced by 18 gr H2O (water) with 237, 1 KJ of Electric energy and 48,7 KJ of thermal energy. Thus theoretically by electrolysis we produce 1 kg or H2 by ~142 MJ of electric energy (HHV) or by ~ 120

MJ (LHV) ( if 22 MJ thermal energy is offered by the environment). The electrolysis technology today can produce 1kg H2 by 158 MJ of electric energy (I.e. by 43.7 KWh), without the compression energy for H2. As a main byproduct, oxygen of 8 kg is produced simultaneously with a quantity of Heavy Water.

2) Combined solar chimney system for power generation and seawater desalination:It is an alternative method of heat and moisture extraction from seawater under the collector of a solar chimney system for power generation and seawater desalination is investigated using one-dimensional compressible flow model. Water and energy are two inseparable items in our lives in recent years; both energy crisis and freshwater shortage problem posing great threat to the humans are attracting great importance around the world owing to rapid development of global economy, fresh water pollution, Increase in population, and improvement of living standards, Seawater desalination is one of the prevalent methods of obtaining large amounts of fresh water. The power generationseawater desalination coupling scheme is very suitable for regions adjacent to the sea or natural alkaline lakes. The combined system consists of four components, i.e. the solar collector, the solar chimney, the turbine generators, and the high-efficiency condenser.


Schematic diagram of CSCS.

02. Water layer. 03. Seawater layer. 04. Thermal resistance bed and ground. 05. Cool & dry ambient air. 06. Warm & saturated operating air. 07. Transparent cover. 08. Guiding cone. 09. Air turbines. 10. Chimney. 11. Water falls trough. 12. High efficiency condenser. 13. Cool & dry ambient air around the chimney outlet 14.Warm ambient air. 15. Condensation water. 16. Water generator. .


16.PrototypeDetailed theoretical preliminary research and a wide range of an experimental plant with a peak output of 50 kW on a site made available by the Spanish utility Union Electrica Fenosa in Manzanares in 1981/82, with funds provided by the German Ministry of Research and technology (BMFT)The aim of this research project was to verify, through field measurements, the performance projected from calculation based on theory, and to examine the influence of individual components on the plants output and efficiency under realistic engineering and meteorological conditions. The main dimensions and technical data for the facility are listed below.

Prototype at Spain

Tower height Tower radius Mean collector radius Mean roof height Number of turbine blades turbine blade profile Blade tip speed to air transport velocity ratio

194.6 m 5.08 m 122.0 m 1.85 m 4 FX W-151-A 1:10


Typical collector air temp. increase Nominal output Collector covered with plastic membrane Collector covered with glass

T=20K 50 kW 40000 m2 6000 m2

Where are the appropriate locations to perform the Floating Solar Chimney Power Stations efficiently? The appropriate locations for FSC's Technology Power Stations installation should have the following characteristics: - High annual solar irradiation on horizontal surface (>1700 KWh/m2) - High insolation (>3000 hours/year) - Low average annual winds (

floating solar chimney technologyfinal

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