tools for sustainability evaluation of · pdf filelife cycle flowchart of biofuel productions...

Nicoletta Patrizi

25th-29th September 2017

Workshop on Life Cycle Assessment and GIS Tools for Energy planning (TW3-TW4)

Tools for sustainability evaluation of RES

Siena

[email protected]

INTRODUCTION

Ecodynamics Group@UNISI

•Recent decades have seen a rising awareness about the need of a transition of human society from the dependence on fossil fuels towards the use of SUSTAINABLE energy sources.

•Two crucial milestones in 2015 :

September December


• The need to replace fossil fuels has posed the attention on

alternative energy sources such as biofuels, in both developed and developing countries.

• The implementation of biorefinery systems for producing biofuels is one of the actions that have been taken against climate change, because such productions are considered a valuable and sustainable alternative to oil refineries.


•The biorefinery concept relies on the integrated approach according to which the value of biomass is maximized by converting it into a variety of products, such as energy vectors, biomaterials, feed and fertilizers.

BIOREFINERY

METHODOLOGIES


•In the last 20 years, various studies have investigated the sustainability of biofuels. •The most used methodologies are Energy analyses, Life Cycle Assessment (LCA), Carbon and Water Footprint and Emergy evaluation. •An integrated approach that combines more than one method is fundamental to outline an environmental profile of biorefinery systems that is as complete as possible, especially to provide a robust support to the decision-making process and to the elaboration of policies about renewable energy sources.

LIFE CYCLE ASSESSMENT (LCA)


•LCA is for sure one of the most helpful methodology usually adopted for investigating sustainability of biofuel production systems. •It is a tool for the analysis of the environmental burdens of products at all stages in their life cycle (‘from the cradle to the grave’). •Thanks to LCA it is possible to investigate the technosphere processes in an accurate and analytical way.

EMERGY EVALUATION


a thermodynamics based function suitable to study sustainability of processes and of territorial systems. available solar energy used up directly and indirectly to make a service or a product; its unit is the solar emergy joule (sej).

•memorization, no conservation

•not a state function

•extensive function

It is

Defined as

Embodied energy


•By means of a conversion factor called Unit Emergy Value (UEV that is the emergy per unit energy), energy embodied in materials and services required to produce a product are converted in a common unit of solar equivalent Joules (sej). • The relevance of emergy relies on the fact that it is an environmental accounting method by means of which it is possible to evaluate the effort of the environment in providing resources, i.e. Nature’s “labor” for re-producing something once it is consumed.

EMERGY EVALUATION


EMERGY EVALUATION

Bastianoni et al., 2007. Emergy as a function of exergy. Energy, 32(7): 1158-1162.


• In this way it is possible to integrate the work done by LCA,

providing a complete view of the evaluated system.

• Emergy can estimate the work done by the environment in

providing resources (i.e. donor-side perspective), while LCA

defines the aspects that generate negative impacts on the

surrounding environment (i.e. user-side perspective).


LCA works here

Biosphere

Emergy works here

Technosphere


•In the light of such considerations, two project research have been carried out with a focus on the integrated sustainability assessment of biorefinery systems by means of LCA and emergy. •The focus of these studies were the hypothetical biofuel production to be implemented by using bioresidues and biowaste produced by agriculture and food-processing industry in two African countries and in the Province of Siena (Italy).

This case study has been developed within a research project named BIOWASTE4SP financed by EU through the FP7 framework. •10 potential feedstock (5 lignocellulosic and 5 starch) have been selected out of 5 partner’s countries (Egypt, Ghana, Kenya, South Africa and Morocco).

Corn stover (i.e. lignocellulosic feedstock)

Cassava peels (i.e. starch feedstock)

The case study of African Countries#1


Life cycle flowchart of biofuel productions based on sugar-rich

feedstocks

Energy system diagram of biofuel production chain. R stands for emergy flow related to local renewable resources; N stands for emergy flow related to local non-renewable resources.


EMERGY EVALUATION

• Emergy of different products is assessed multiplying mass or energy quantities by a transformation coefficient, called Unit Emergy Value (UEV). • As the selected feedstocks were chosen for their potential of transformation into

biofuels, it has been calculated their UEV according to the related content of glucan.

• Dividing the specific emergy by the content of glucan per unit of mass

LIFE CYCLE ASSESSMENT • characterization method CML-IA, the updated version of CML 2 Baseline Method

2000: ⁻ Acidification, ⁻ Eutrophication ⁻ Global Warming.

sej/gof glucan = (sej/g) / (g of glucan/g)


CASSAVA PEELS PROCESSING

Item Unit Quantity Primary data Secondary data

Transport to plant kg km 176200 Assumption

Input

Feedstock CASSAVA PEELS kg 3524 This study

Enzymes Enzymes kg 1.27 Le et al., 2013 -

Additives NaOH kg 3.80 Le et al., 2013 Ecoinvent database,

2014

Urea kg 3.80 Le et al., 2013 Ecoinvent database,

2014

DAP kg 3.80 Le et al., 2013 Ecoinvent database,

2014

Energy Electricity kWh 355.70 Le et al., 2013 Ecoinvent database,

2014

Fuel Coal kg 759.49 Le et al., 2013 Ecoinvent database,

2014

Plant Concrete kg 20.18 Patrizi et al., 2013 Ecoinvent database,

2014

Reinforcing steel kg 11.35 Patrizi et al., 2013 Ecoinvent database,

2014

Output Product Ethanol kg 1000

UF 1 t of bioethanol

INVENTORY - cassava peels feedstock


RESULTS# LCA

2208.86

1559.30

0.00

500.00

1000.00

1500.00

2000.00

2500.00

TOTAL Transport Addi ves Plant Energy Fuel

kgCO2eq

GlobalWarmingPoten al

CORNSTOVER CASSAVAPEELS

higher energy requirement of lignocellulosic-based biorefineries with respect to the starch-based ones, as the pretreatment phase represent a crucial step in order to make cellulose and hemicellulose accessible for the subsequent enzymatic hydrolysis

A similar trend was observed for the Acidification, for which the production based on corn stover produced 10.24 kg SO2 eq against 3.53 kg SO2 eq associated to cassava peels.


POLAR REPRESENTATION: segment lengths are proportional to UEV (in sej g-1 of glucan) and slopes indicate the percentage renewability of the total emergy supporting the production system, from 100% (right end of horizontal axis) to 0% renewability (left end). A system with 50% renewability will fall on the vertical axis.

UEVs based on glucan content suggest that corn stover is less efficient in transforming the past and present solar energy needed for the production system into glucans. This is mainly due to the fact that it has a lower glucan content against cassava peels feedstock. On the contrary, the lowest UEV, i.e. highest efficiencies, is reported for cassava peels; the high sugar content and low production intensity are responsible for this good result.

RESULTS# eMergy


The case study of the Province of Siena#2

• In the Province of Siena (Italy), 37% of the total area is devoted to agriculture and the main crop productions are wheat, oat and barley.

• A great potential availability of crop residues can be used as feedstock for second generation bioethanol production.

• This territory has another peculiarity: geothermal heat that is used for electricity production, which supply about the 98% of the electricity consumed in the provincial area. Along the electricity production process a steam flow is generated that is usually re-injected into geothermal reservoir.

• In this case study we have hypothesized the joint use of these two residual flows (straw and steam) as input for the implementation of a second generation bioethanol production chain, taking inspiration by the Danish IBUS (Integrated Biomass Utilization System).


Collection of straw Transport Plant

Biorefinery ETHANOL

Geothermal power plant

Agricultural processes

Straw

Heat

Electricity

Grains

The IDEA


The quantity needed

• In the selected municipalities in the period 2006-2010 about 60,000 tons of straw.

• Around 32000 ton required for bioethanol production approximately corresponds to the 55% of the total straw production of these 19 municipalities, and the 28% of the total straw production within the entire Province of Siena.

43000 tons of gasoline

USE

7000 tons of ethanol

NEED To replace 10%

of gasoline 0.22t of Eth

per ton of straw

31600 tons of straw

NEED


The system

• The location of the biorefinery should be in the NW part of the Province of Siena, in the municipality of Radicondoli.

• This location would enable the bioethanol production plant to be close to geothermal wells and, at the same time, quite far from urban areas.

• Municipality involved in the production chain are those located within 70 km from

the plant to being complaint with the Italian law on the sustainable use of biomass.

Radicondoli

The Province of Siena ITALY

10 km


• The Emergy Investment needed for the bioethanol production is defined as the quantity of inputs, expressed in emergy terms, that must be added to an existing systems or processes (in our case cereal and electricity production), in order to obtain further output(s) or optimize the use of resources.

• As investment we consider only work, fuels and machineries requested for straw collection and transport to the plant and all the inputs for the bioethanol production within the biorefinery plant, except for the heat, that is by-product of the geothermal plant.

RESULTS# eMergy


RESULTS# eMergy

ITEM DETAIL INPUT * Unit yr-1

Unit

UEV (semj unit-1)

baseline 9.26E+24

Emergy sej yr-1

POST AGRICULTURAL PHASE machineries for straw collection diesel 7.12E+08 g 2.86E+09 2.04E+18 machineries for straw collection Steel 2.01E+08 g 3.38E+09 6.80E+17 human work for straw collection human work 9.21E+08 J 4.41E+06 4.06E+15

TRANSPORT OF STRAW TO THE BIOREFINERY

light transport Trakker 1.72E+12 gkm 5.38E+04 9.23E+16

INDUSTRIAL PHASE

water Water 6.20E+08 g 1.84E+06 1.14E+15 plant Concrete 1.42E+08 g 1.78E+09 2.53E+17 plant Reinforcing steel 8.00E+07 g 3.38E+09 2.71E+17

energy Electricity 2.16E+13 J 1.35E+05 2.90E+18

Process steam (geoth) 1.25E+14 J 0.00E+00

0.00E+00

Propane 3.42E+10 J 6.65E+04 2.27E+15

TOTAL EMERGY INVESTMENT 6.24E+18

UEI** sej/g

output bioethanol produced 7.06E+09 g 8.84E+08

43.5%

1.50%

55.5%

47%


RESULTS: EMERGY BASED CBA

ITEM DETAIL AMOUNT

t yr-1 EM

sej yr-1

EMERGY INVESTMENT BIOETHANOL FOR SUBSTITUTION*

7060 6.24E+18

EMERGY SAVED GASOLINE SUBSTITUTED**

4300 1.27E+19

*UEI bioethanol 8,84E+08 sej/g (this study) vs

**UEV gasoline: 2.95E+09 sej/g (Bastianoni et al. 2009)

BENEFIT DOUBLES THE INVESTMENT

= UEI of bioethanol is three times lower than UEV of gasoline


BIOREFINERY STRAW PRODUCTION AND

HARVESTING TRANSPORT

TRANSPORT AND DISTRIBUTION OF

BIOETHANOL BIOETHANOL

INPUTS: wheat, oat and barley

production and harvesting

STRAW STRAW

1 2 3

4

OTHER OUTPUTS emissions in air, water and soil

OUTPUT 528.67 kg

CO2eq

INPUTS: trucks and fuels

INPUTS: concrete, reinforcing steel, electricity, cooling energy,

steam, propane

INPUTS materials and energy

OUTPUT 52.82

kg CO2eq

OUTPUT 20.02

kg CO2eq

OUTPUT CO2eq




88% 9% 3%

1 t bioethanol 601.51 kg CO2eq

UF 1ton bioethanol

RESULTS# LCA


RESULTS: LCA bioethanol substitution

1 t bioethanol = 72.83 kg CO2eq

without straw therefore

7,060 t bioethanol =

+ 514 t CO2eq

This lead

s 13,259 t CO2eq reduction of the territorial emissions

= -1% gross CO2eq of the Province of Siena

-2.2% CO2eq emissions of transport sector - 1.4% CO2eq emissions of energy sector

-4300 t of gasoline consumption = -13,773 t CO2eq


•To have a whole perspective of the case studies from a sustainability viewpoint, we have adopted LCA and emergy jointly.

•By means of LCA, it was possible to evaluate and compare the potential environmental impacts produced by biofuel production phase.

•Such a work has been integrated by means of emergy evaluation of the previous phase, i.e. the cultivations that produce biowaste. In this regard emergy provides a fundamental support to the evaluation as it works very well for evaluating systems having an interface between natural and man-made capital.

CONCLUSIONS


Nicoletta Patrizi [email protected]

THANK YOU


CONCLUSIONS: African Countries#1

•The higher energy requirement for pretreating lignocellulosic biomass in order to make sugars available for the subsequent fermentation process results in higher impact categories for lignocellulosic feedstock (i.e. corn stover).

•Emergy outcomes highlighted that the starch rich feestock (i.e. cassava peels) proved to be the most promising residues from an emergy viewpoint, as it had the lowest UEVs and the highest percentage renewability.

•Such results identify biorefinery system based on cassava peels as the best one from a sustainability viewpoint, from both user and donor side perspectives.


CONCLUSIONS: the Province of Siena#2

THE QUESTION WAS: IS THIS SYSTEM ENVIRONMENTALLY FAVOURABLE?

THE ANSWER IS: YES

EMERGY EVALUATION showed that the benefit due to

the saving in gasoline, in emergy terms, doubles the emergy

investment.

LIFE CYCLE ASSESSMENT showed that the substitution of

the 10% of gasoline consumption leads to a decrease of the CO2eq emissions of the territory of the

Province of Siena

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