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ENVIRONMENTAL ASSESSMENT OF WOOD DERIVED HEMICELLULOSIC ETHANOL USING ALTERNATIVE LCA MODELS

ENVIRONMENTAL ASSESSMENT OF WOOD DERIVED HEMICELLULOSIC ETHANOL USING ALTERNATIVE LCA MODELS. Rachel Bowman, Anthony Halog Forest Bioproducts Research Initiative University of Maine Massachusetts Institute of Technology Western Kentucky University ACLCA Conference. Presentation Format.

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ENVIRONMENTAL ASSESSMENT OF WOOD DERIVED HEMICELLULOSIC ETHANOL USING ALTERNATIVE LCA MODELS

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  1. ENVIRONMENTAL ASSESSMENT OF WOOD DERIVED HEMICELLULOSIC ETHANOL USING ALTERNATIVE LCA MODELS Rachel Bowman, Anthony Halog Forest Bioproducts Research Initiative University of Maine Massachusetts Institute of Technology Western Kentucky University ACLCA Conference

  2. Presentation Format • Project Overview • Why? • Description of System • Functional Unit • Assumptions • Graphs and Results for LCA Models • Pros and Cons of LCA Models • Conclusions

  3. Project Overview • Use Lifecycle Assessment (LCA) to evaluate the environmental impact of wood derived bioethanol • Complete LCA with commercial SimaPro model, Eco-LCA , and openLCA • Compare results of three LCAs and determine which model best represents the data • Learn more about openLCA and Eco-LCA

  4. Why? • Energy crisis worldwide calls for new, renewable energy sources like bioethanol • Many LCAs have been performed of corn derived bioethanol but not wood derived– wood doesn’t compete with food • The near-neutral extraction process is fairly new and knowing its full lifecycle before widely implementing it is important

  5. Description of System Schematic of Near-Neutral Extraction Process to produce bioethanol1

  6. Description of System • Hemicellulose is extracted before pulping • Reagents: anthraquinone and green liquor (sodium hydroxide, sodium sulfide, sodium carbonate) • Green liquor- breaks apart hemicellulose • Anthraquinone- works as catalyst to maintain pulp quality/quantity

  7. Functional Unit • 9.8x109 Btu worth of ethanol (density .789 g/mL and 75,700 Btu per gallon) • 39.5 tonnes ethanol, 45.1 tonnes acetic acid, 1000 tonnes pulp produced daily • From 2,166 tonnes of wood chips • From Mao’s provisional data

  8. Assumptions • Average moisture content of the wood is 46% • All wood is assumed to be a product of the Northeast Region of the United States • Wood chipped in the field using mobile wood chipping technology • Wood is composition 42.6% cellulose, 29.7% hemicellulose, 27.5%lignin, and .2% ash on a dry wood weight basis

  9. Allocation • SimaPro 7.1 model was allocated by the mass of the products • openLCA model would have been allocated by mass of products • Eco-LCA allows only for economic allocation • Allocated economically by value of wood chips, Kraft pulp, acetic acid, and bioethanol

  10. Data Collection • Primary data– consultation with Dr. Genco in Chemical Engineering Dpt. • Mao’s original WinGEMS model from thesis for LCI input-output data • Secondary data: • Wooley’s NREL Report • US Data (preferrably Northeast [Maine]) • Relevant timeframe • Relevant processes

  11. LCI Databases Used • SimaPro • Ecoinvent • Franklin • USLCI • Eco-LCA • Eco-LCA standard ecosystem goods and services database • OpenLCA • Would have used Ecoinvent, like SimaPro

  12. SimaPro 7.1 Normalized Results • Fossil fuels, respiratory inorganics, climate change, and acidification are most affected impact categories • Biggest contributing processes to these environmental impacts are the liming/causticizing process, acid hydrolysis, wood chipping/wood production, and hog fuel boiler • Heavy fuel oil consumption in the liming process contributes most to the fossil fuel use • large amounts of oil must be pumped into the system for the liming process to take place • Liming process also heavy in respiratory inorganics

  13. SimaPro 7.1 Normalized Results– Mass Allocation Normalized Results of SimaPro Model

  14. SimaPro 7.1 Normalized Results– Economic Allocation

  15. SimaPro 7.1 Single Score Results– Mass Allocation Single Score Representation of SimaPro model

  16. SimaPro 7.1 Single Score Results– Economic Allocation

  17. SimaPro 7.1 Single Score Results • The liming and causticizing process carries the heaviest environmental impact of all the processes in producing bioethanol • Heavy fuel oil consumption in the liming process • Respiratory inorganic output of the process, • sulfate ions being released during the causticizing process

  18. SimaPro 7.1 Single Score Results • Other process that has a heavy impact is the wood chip production. • In line with the Bhander/Halog study that showed that wood chip production had a heavy environmental impact • Includes everything from the planting of the trees to the felling and chipping process, • Heaviest in climate change and respiratory inorganics • The climate change category includes green house gas emissions from gases such as CO2, SOx, NOx, and CH4.

  19. Eco-LCA Emissions Results Emissions Normalization of Eco-LCA model

  20. Eco-LCA Emissions Results • Showed that the pulp production process is far heavier in green house gas emissions than logging, acetic acid, or ethanol production • Heaviest impact categories were ethanol and ammonia, in land, air, and water • Ammonia accounted for is most likely the respective inorganic material that is shown in SimaPro model produced from the liming/ causticizing process and wood chipping

  21. Eco-LCA Emissions Results • Emissions mostly from pulping process, which makes sense since the model is allocated economically • Particulate matter (<10 µm) is shown, probably some of the climate change SimaPro is accounting for

  22. Eco-LCA CO2 Emission Results CO2 Normalization of Eco-LCA model

  23. Eco-LCA CO2 Emissions Results • Show that more carbon is actually sequestered as a result of the production of ethanol than is emitted • trees being used to feed the pulping plant sequester more carbon during growth than is emitted in pulping process • Kraft pulping process doesn’t use (much) external energy • Energy required is produced in the hog fuel and recovery boilers • Plant is not using any external electricity from fossil fuels like coal or natural gas that would increase emissions

  24. Eco-LCA Energy Consumption Results Energy Normalization of Eco-LCA model

  25. Eco-LCA Energy Consumption Results • Logging and chipping processes consume the most energy in process. • heaviest in sunlight and wood energy • Imply that trees absorb sunlight as part of their growth process • Some of the wood waste is later used to produce steam in the hog fuel boiler • The other energy consumed in the process was generally low in all categories, especially in that of fossil fuels. • Any fossil fuel use can be attributed to the equipment used for logging and chipping, such as mobile wood chippers or the trucks that transport the chips to the Kraft Pulp Mill

  26. Eco-LCA Water Consumption Results Water Normalization of Eco-LCA model

  27. Eco-LCA Water Consumption Results • The majority of the water consumed in pulping process • Can be attributed to economic allocation • Consumption of water for logging is the highest with respect to agriculture and feedstock water, • Powerplant water had the highest total consumption in the process

  28. Eco-LCA Water Consumption Results • Can likely be attributed to the fact that water coming to the Kraft Pulp Mill would be coming from a supply other than the public water source and being filtered and treated separately from the public drinking water. • Water supply in any chemical plants would also be processed and filtered separately from the public water supply • Water supply for the ethanol and acetic acid production is assumed to be the same as for the Kraft Pulp Mill

  29. OpenLCA (The Abbreviated Version) • Issues getting openLCA database to load • Designed to simply import complete SimaPro 7.1 model into openLCA in EcoSpold format • EcoSpold formatting only available with SimaPro Developer version • FBRI only has Analyst version Bottom Line: openLCA model was never completed due to software issues

  30. Pros and Cons- SimaPro • Cons: • Cost-- ~$14,000 (US) for permanent license for developer version • Doesn’t account for ecosystem goods or services • Doesn’t show graphically what specifically is contributing to each impact category • Minimal US specific data • Should improve in future versions as LCA becomes more popular in North America

  31. Pros and Cons- SimaPro • Ecoinvent database was the most comprehensive database of models • Allows simple loading of outside data and processes into the program • Extensive tutorials, user guides, etc. for LCA beginners • Many options for allocating, characterizing, and normalizing data (methods) • Specifically used Ecoindicator in this study

  32. Pros and Cons- Eco-LCA • Cons • Not as many options in general as SimaPro • Only set up to handle economic allocation • Hard to enter outside data • Only very simple tutorial available, a little difficult for an inexperienced user to figure out • Difficult to transfer results out of flashplayer for viewing in papers, presentations, etc.

  33. Pros and Cons- Eco-LCA • Pros • Includes ecosystem goods and services– allows user to get bigger and better view of lifecycle • While no user guide, developers are easily accessible for questions • Free • Provides graphical representation of different substances that are contributing to an impact category

  34. Pros and Cons- OpenLCA (In a theoretical world where SimaPro Developer was available) • Cons • Individual database didn’t load– what would someone do without another imported model? • User manual is difficult to access but does exist • http://www.openlca.org/uploads/media/Guide_to_testing_the_openLCA_framework_Alphaversion.pdf • Still being developed– still some issues • A little difficult to learn howto use

  35. Pros and Cons- OpenLCA (In a theoretical world where SimaPro Developer was available) • Pros • Includes file format converter to directly import data from another LCA model in SimaPro or Excel • Flows set up allows for the production of a system model as well as an LCA • Free and publicly available • Good graphical representation once LCA is complete

  36. Conclusions • Mass and economic allocation have about same results in SimaPro, so economic allocation is probably accurate • Eco-LCA provides best representation of this data set despite allocation only economically • Results of openLCA would have looked a lot like the SimaPro results, but provided an input-output model as well

  37. Conclusions • The real advantage with Eco-LCA is the inclusion of ecosystem goods and services– gives much better ‘big picture’ outlook of system • Using a free program makes it so that one can report their conclusions to anyone, whether they have a license for the program or not

  38. Conclusions • It appears that the actual results from the Eco-LCA and SimaPro models are pretty similar • Eco-LCA has different impact categories, but one can see how the high impact substances contribute to the more general impact categories in SimaPro

  39. Acknowledgements • Funding-- provided by The National Science Foundation grants EEC-06 48793, EPS-05 54545 • REU program/FBRI • Dr. Halog • Dr. Genco • Shashi Dhungel and Binod Neopane, graduate students

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