Studying the consequence of different system choices in LCA for ethanol production:
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Studying the consequence of different system choices in LCA for ethanol production: An assessment b Mahasta Ranjbar a, Réjean Samson b and Paul R. Stuart a a NSERC Environmental Design Engineering Chair CIRAIG - Interuniversity Reference Center for the Life Cycle Assessment, Interpretation and Management of Products, Processes and Services Chemical Engineering Department École Polytechnique Montreal October 2009 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 2 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 3 Introduction; General review of ethanol production Climate change Ethanol Vs. Fossil fuels • Environmental advantages Feedstocks Starchy crop farming Crop residues collection Starchy crop ethanol production Energy crop farming Municipal and industrial wastes Cellulosic ethanol production Co‐products Forest residue collection Sugarcane farming Sugarcane ethanol production Co‐products Transportation fuel 4 Introduction; General review of ethanol production First generation vs. second generation (Kadam 2002, Kemppainen and Shonnard 2005, WONG 2008 , Department of Energy) Feedstock preparation, pre-treatment, hydrolysis, fermentation and product recovery Ethanol vs. co-products (Aden, Ruth et al. 2002; Fu, Chan et al. 2003; OLSON, AULICH et al. 2003; Kemppainen and Shonnard 2005; DOE 2008) Bagasse in sugar cane-to-ethanol conversion Corn syrup, corn oil, corn gluten meal, corn gluten feed and food-related products in wet milling of corn-toethanol conversion Animal feeds in dry milling of corn-to-ethanol Electricity in cellulosic feedstocks-to-ethanol 5 Introduction; Life Cycle Assessment (LCA) Life cycle assessment (LCA) is recognized as a systematic and practical approach to evaluate the environmental performance of a product, process or activity (ISO 14040) The reason for carrying out the study, the intended audience and the activities included Quantifying of all inputs and outputs for the entire life cycle of a product, process or activity The evaluation of potential human health and environmental impacts of the releases An analysis of major contributions, sensitivity and uncertainty analysis leads to the conclusion 6 From Inventory to Impact Assessment Impact Inventory Production processes Energy production Waste management Air, water and land emissions: CFC Pb Cd HAP VOC DDT CO2 SO2 NOX P Dust Transport Resource Depletion Resource depletion Global warming Ozone depletion Ecotoxicity Toxicity Smog Acidification Eutrophication Etc… Mortality & disease Ecosystem destruct Solid wastes Solid wastes Problem Approach “Midpoint” Damage Approach “Endpoint” Aesthetic value Single indicator Resource depletion Solid wastes PRECISION 7 Environmental performance of ethanol production Using Life Cycle Assessment methodology(ISO 14040) Methodological choice • System boundary • Environmental impacts • Allocation procedure 8 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 9 Literature review Many articles in this area LCA study Ethanol production 26 LCA articles Following LCA methodology Looking at more than one environmental impact category Using allocation procedures 10 Literature review All kind of feedstocks First generation: corn grain, cassava, sugar beet, wheat grain and sugarcane Second generation : agricultural and forest residues, wood and municipal solid waste 11 Literature review; Methodological choices The answer for a sustainable ethanol production is highly dependant on the chosen methodology, design variables and assumptions used. (Sheehan, Aden et al. 2004; Hu, Tan et al. 2006; Weiss, Patel et al. 2007) Methodological choices : Using fuel ethanol in different forms has different performance based on the chosen environmental impacts.(Kim and Dale 2006) Choice of allocation procedures has a significant impact on fuel ethanol (Kim and Dale 2002; Bernesson, Nilsson et al. 2006; Curran 2007;Leng, Wang et al. 2008) The reduction of GHGs by using biofuel is particularly sensitive to the source of energy used in the process. (Fu, Chan et al. 2003) The environmental impacts of ethanol depend on the type of feedstocks. (Kemppainen and Shonnard 2005) 12 Literature review; 1. System boundary To include all important environmental burdens To avoid all the insignificant streams Cradle-to-grave (1) vs. cradle-to-gate (2) (1) : a holistic perspective of environmental impacts (Kadam 2002; Fu, Chan et al. 2003; Sheehan, Aden et al. 2004; Zhiyuan, Gengqiang et al. 2004; Bernesson, Nilsson et al. 2006 and...) (2) : an opportunity to point out the hot-spots (Panray Beeharry 2001; Kim and Dale 2002; Kemppainen and Shonnard 2005; Botha and von Blottnitz 2006; Malca and Freire 2006 and ...) 13 Literature review; 2. Environmental impacts Midpoint approach is more certain but sometimes is has lower relevance Endpoint indicators have higher relevance but more uncertainties Category Midpoint (Impact category) Endpoint (Damage category ) Number of pubs 20 6 14 Literature review; Environmental impact category Global warming (GHGs calculation) Carbon dioxide, Nitrous oxide and Methane emissions (Sheehan, Aden et al. 2004; Fleming, Habibi et al. 2006; Reijnders and Huijbregts 2007) Only carbon dioxide emission (Panray Beeharry 2001; Botha and von Blottnitz 2006; Kalogo, Habibi et al. 2007; Gabrielle and Gagnaire 2008) Energy used Energy content (Durante and Miltenberger 2004; Leng, Wang et al. 2008) Energy consumed (Kim and Dale 2005; Fleming, Habibi et al. 2006; Hu, Tan et al. 2006) Acidification and eutrophication (Puppan 2002 ; Hu, Pu et al. 2004; Sheehan, Aden et al. 2004) Agricultural process such as feedstock cultivation Pollution of ground and groundwater by fertilisers and pesticides 15 Literature review; 3. Allocation procedure Multiple-products processes The selection of how to decide what share of the environmental burdens of the activity should be allocated to ethanol and other co-products Allocation procedure (ISO 14044) Avoid allocation whenever it is possible Where allocation cannot be avoided, the partitioning model should be applied based on physical properties Where physical relationship cannot be used alone, allocation should be based on the other relationship 16 Literature review; Allocation procedure Avoiding allocation pros: • Model the indirect effects (Ekvall and Finnveden 2001) • Applicable when the market is restricted (Börjesson 2009) • There is no need to divide the impacts by assumption cons: • Appropriate results when appropriate data for the indirect effects (Ekvall and Finnveden 2001) • Different substitution for co-products ; eg: for DDGS, soybean meal (Kim and Dale 2005), soybean oil(Kim and Dale 2002) or corn/soybean meal(Hill, Nelson et al. 2006) • Complicated (Weidema 1993) 17 Literature review; Allocation procedure Physical allocation (Mass and energy) pros: • Available data and easy interpretation (Malca, 2004) • Independent of time cons: • Targeted product and co-product in a reasonable amount (Nguyen and Gheewala 2008 ;Kim and Dale 2002) Economical allocation pros: • Appropriate when amount of products are very dissimilar (Börjesson 2009) cons: • Dependent of time (Börjesson 2009) 18 Problem identification Which methodological choices are the best? What are the consequences of different choices in the final results? 19 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 20 Objectives To assess a body of knowledge related to LCA studies of ethanol production through different feedstocks in order to identify some of the methodological choices that have been made To evaluate the consequences of methodological choices for ethanol production in order to propose an appropriate LCA methodology 21 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 22 Overall approach Comparison the methodological choices in a case study System boundary Environmental impact category Allocation procedure Selection the most appropriate choices (The best methodology) Applying the best methodology in the case study Evaluation of environmental performance 23 Exploration of the methodological choices; Case study content Base case done by Kemppainen et al. [2005] Mass and energy balances based on report by National Renewable Energy Laboratory (NREL) (Wooley, Ruth et al. 1999) Timber as feedstock (Kemppainen and Shonnard 2005) The feed rate is 83333 kg/h to produce 60 MG ethanol/Year 24 Application of LCA methodology; 1. System boundary Feedstock: Cultivation Collection Transportation Raw material Chemicals: Production Transportation T Raw material collection T Chemicals Electricity Product conversion Process use Ethanol product Ethanol as fuel Ethanol Sold to grid Co2 Ash Landfill Gypsum Methane Landfill Waste treatment Cradle-to-gate : The end-use combustion phase is the same when ethanol is assumed as fuel Enables to describe a status-quo situation Increase the change to identify the hot-spots for improvement 25 Characterisation; 2. Environmental indicators Endpoint (damage category) vs. Midpoint (Impact category) Methodological choices System boundary Method I Method II Cradle‐to‐gate Cradle‐to‐gate human toxicity, respiratory effects, ionizing radiation, ozone layer Human health, depletion, photochemical oxidation, Damage Impact Ecosystem aquatic ecotoxicity, terrestrial Environmental impact category quality, Climate category ecotoxicity, terrestrial acidification, category (Midpoint) (Endpoint) change, aquatic acidification, aquatic Resources eutrophication, land occupation, global warming, non-renewable * Impact 2002+ energy, mineral extraction 26 Characterisation; Environmental impacts Normalized value 27+ based on Impact 2002 Characterization; 3. Allocation procedure Raw material T Raw material collection T Chemicals Sold to grid Electricity Product conversion Process use Ethanol product Co2 Ash Landfill Gypsum Methane Landfill Ethanol Multi-output process 28 Characterization; Allocation procedure Avoid allocation whenever it is possible (ISO 14044) Where allocation cannot be avoided, the partitioning model should be applied based on physical properties or other relationship (ISO 14044) Methodological choices Method I Method II System boundary Cradle‐to‐gate Cradle‐to‐gate Environmental impact category Impact category (Midpoint) Impact category (Midpoint) Allocation procedure Avoiding allocation Physical allocation 29 Characterization; Normalized value based on Impact 2002 + Allocation procedure Difference is obtained because of partitioning In method II, a part is taken for electricity How big is this part? More appropriate results for Method I (avoiding allocation)30 Selection of methodological choices System boundary Cradle-to-gate Environmental impacts Impact category (Midpoint) Allocation procedure Avoiding LCIA method Impact 2002+ 31 Results Impact category Unit Total Carcinogens kg C2H3Cl eq 0.000124 InNon‐carcinogens order to determine impact is more kg C2H3Cl which eq 5.11E‐05 Respiratory inorganics kg PM2.5production eq 9.85E‐06 significant in ethanol Ionizing radiation Bq C‐14 eq 6.42E‐02 Normalization Ozone layer depletion kg CFC‐11 eq 1.42E‐09 Internal Respiratory organics kg C2H4 eq 5.37E‐06 Categorieskg are divided of the values Aquatic ecotoxicity TEG water by a function 0.392846 obtained for the base case studied alternatives Terrestrial ecotoxicity kg TEG soil 0.110904 TerrestrialExternal acid/nutri kg SO2 eq 0.000211 Categoriesm2org.arable are evaluated based on0.003335 the global Land occupation impact results of a chosen reference Aquatic acidification kg SO2 eq 6.98E‐05 Aquatic eutrophication kg PO4 P‐lim 6.69E‐07 Global warming kg CO2 eq 0.008663 Non‐renewable energy MJ primary 0.234338 Mineral extraction MJ surplus 0.000132 32 Results; Normalization External normalization Based on corn-to-ethanol process • First generation vs. second generation • Well-known process Assumptions • Cultivation of corn • Production of chemicals • Transportation of raw material and chemicals to the mill Methodological choices • Cradle-to-gate • Midpoint • Avoiding allocation 33 Discussion; Normalized results Emissions associated with heavy metals from combustion using diesel and petrol Emissions associated with corn cultivation Positive result : the alternative performs worse than referential system Negative result : the alternative performs better than referential system Environmental evaluation metrics : Global warming Acidification/Eutrophication Land occupation 34 Outline Introduction General review of ethanol production Overview of Life Cycle Assessment Literature review Objectives Methodology Characterisation of methodological choices Exploration of methodological choices Case study content Application of LCA methodology System boundaries Environmental impacts Allocation Results and discussion Conclusion 35 Conclusion ; Based on literature review Important methodological choices in ethanol LCA System boundary Environmental impacts Allocation Contradictory conclusions regarding The activities which were included or excluded The selection of data sources The division of the environmental emissions among products No generic rule for their selection It has to be considered case-by-case Different screening metrics would result different environmental decision 36 Conclusion; Based on case study Woodchips-to-ethanol System boundary Cradle-to-grave • Ethanol as fuel Cradle-to-gate Environmental impacts Damage category • Less follow-up data around the process Impact category Allocation procedures Avoiding allocation Physical allocation • The division of emission between ethanol and electricity 37 Conclusion; Based on case study Normalization method Internal methods • Based on the chosen LCIA method External methods • Based on the process design (corn-to-ethanol) – Well-known process Woodchips-to-ethanol vs. corn-to-ethanol Environmental evaluation metrics • Global warming • Land use • Acidification/eutrofication Woodchips-to-ethanol has a better environmental performance 38 Acknowledgments NSERC- Environmental Design Engineering Chair CIRAIG - Interuniversity Reference Center for the Life Cycle Assessment, Interpretation and Management of Products, Processes and Services 39 Studying the consequence of different system choices in LCA for ethanol production: An assessment Thank you Questions?
