Biofuels from Biomass: LCA Considerations

Transcription

1 Biofuels from Biomass: LCA Considerations CRC Workshop on LCA of Biofuels, Argonne Andy Aden, PE Sr. Research Supervisor Biorefinery Analysis October 21, 2009 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, operated by the Alliance for Sustainable Energy, LLC.

2 Life Cycle Assessment - Perspective Life Cycle Assessment is a tool Ideal for comparing new technologies to the status quo Brings stakeholders into the dialog Reveals unexpected environmental impacts (but no show-stopping surprises) Take Home Messages 1. Follow ISO guidelines whenever possible - System expansion if possible, then allocation - Average operations vs. marginal changes (attributional ti vs. consequential), consider which is most appropriate and if data exists 2. Modern tillage and crop/land management practices can significantly improve sustainability of biofuels 3. Biorefinery process design has a large impact environmental metrics - Utility systems have a huge impact on overall net energy and GHG 4. Uncertainty - Many environmental uncertainties remain - New methods of quantifying 2

3 NREL has a long history of LCA success and maintains significant expertise Power LCAs: - Dedicated biomass IGCC - Pulverized coal boiler - Biomass residue/coal cofiring - NGCC - Direct-fired biomass residue Fuel LCA: - Corn stover to ethanol (Iowa specific) - Biodiesel from soybeans, jatropha - EISA 2022 Scenario (>4 biomass feedstocks) - Corn stover to gasoline & diesel (pyrolysis) Hydrogen: - SMR - Wind/electrolysis NREL also maintains the US LCI Database 3

4 LCA is a tool for dialog Involving stakeholders at the start and throughout such studies builds trust and confidence. It also helps to sort out the uncertainties of the science from the uncertainties of the moral and ethical choices we need to make. 4

5 Conversion to Fuels has Numerous Pathways Biomass Feedstocks Intermediates t Transportation Fuels Lignocellulosic Biomass (wood, agri, waste, grasses, etc.) Ag residues, (stover, bagasse) Gasification Pyrolysis & Liquefaction Syn Gas Bio-Oils Lignin Fermentation Catalytic synthesis FT synthesis MeOH synthesis HydroCracking/Treating Catalytic upgrading Ethanol & Mixed Alcohols Diesel* Methanol MTG Gasoline* Diesel* Gasoline* & Diesel* Sugar/Starch Crops (corn, sugar cane, etc.) Hydrolysis Sugars APP Catalytic pyrolysis APR Diesel* Gasoline* Hydrogen Fermentation Ethanol, Butanol, Hydrocarbons Natural Oils (plants, algae) Transesterification Hydrodeoxygenation Biodiesel Green diesel National Renewable Energy * Blending Products Laboratory Innovation for for Our Energy Future

6 Utility systems play a significant role in the net energy ratio of a process From The Importance of Utility Systems in Today s Biorefineries and a Vision for Tomorrow by T. Eggeman and D. Verser, Applied Biochemistry and Biotechnology, Vol ,

7 Effect of Residue Removal on Soil Carbon Flux Farmers can seq C in plant & soil or recycle C between field and etoh process % = % of max removable stover Maximizing stover collection = less carbon in the soil but greatest amount of CO2 avoided per acre 7

8 There are always tradeoffs LCA continued Sheehan, et.al. Journal of Industrial Ecology, Volume 7, Number 3-4 4, % less oil use (every mile traveled requires 5% of crude oil compared to conv gasoline) 106% lower GHG 12x higher NOx (CO2, CH4, N2O) (from soil emissions) 8

9 Recent studies Williams, et.al. Environmental and Sustainability Factors Associated with Next-Generation Biofuels in the U.S.: What Do We Really Know?, ES&T May 2009 Factors considered include GHG emissions, air pollutants, soil health and quality, water use and water quality, wastewater, solid waste, biodiversity, and land use Next generation feedstocks largely expected to fare better on most of the factors, but the magnitudes of these vary significantly among feedstocks Identified significant uncertainties, recommended research o Field trials inclusive of many different conditions (Sun Grant) o Land use research, standardized approaches, etc. o Optimize conversion efficiencies o Further health impacts studies. Foust, et.al. An economic and environmental comparison of biochemical and thermochemical lignocellulosic ethanol conversion processes, Cellulose May/June Emissions profiles between biochemical and thermochemical ethanol are substantially similar 9

10 EISA 2022 Sustainability Assessment - using SimaPro v7.1 St tarch-based Feedstocks losic Feedst tocks Corn Grain Corn Stover Wheat Straw Switchgrass Dry Mill Biochemical Denatured Ethanol Use in Vehicle Tool NOT for policy assessment but for guiding sustainability metrics development and technology development Cellul Forest Residue Thermochemical Simultaneously consider high-throughput (EISA-scale), advanced system (mature EISA) designs for all life cycle stages Indirect land use not considered National average conditions Differences among locations explored in sensitivity analysis 10 10

11 Greenhouse Gas Emissions kg CO 2 Equiv. per km traveled) Greenhouse Ga as Emissions ( Advanced Corn Grain Dry mill Corn Stover Switchgrass Biochemical Wheat Straw Forest Residue Thermochemical Gasoline 2005 Gasoline 2022 Draft results Results are for E85 Results are not used for EPA s rulemaking for biofuels E85 with corn in 2005 was 19% lower than gasoline 2005 Feedstock production and harvesting Net emissions Preprocessing Feedstock transportation Conversion Ethanol distribution Vehicle operation Feedstock CO 2 absorption 11 11

12 Sensitivity and Uncertainty Analysis Inherent uncertainty in projecting results to 2022 Sensitivity Uniform random distributions Regional variations, future projections, LCA factors Yields (farming, refinery), composition, farming practices, co-product credits Includes different allocation for irrigation for residues Principle Component Analysis (PCA) to identify significant parameters Uncertainty For significant parameters, assign probability distribution (triangular, normal) Does not include different allocation for irrigation Monte Carlo analysis 12

13 Greenhouse Gas Emissions Greenhous se Gas Emissio ons (kg CO 2 Eq quiv. per km tra aveled) Draft results Gasoline Several Metrics - GHG emissions - Consumptive water use - Fossil energy demand Advanced Corn Grain Dry mill Corn Stover Uncertainty Base case 5th/95th percentile Switchgrass Biochemical Wheat Straw Forest Residue Thermochemical Parameters with greatest impact across all metrics: - Biomass Yield - Irrigation - Nitrogen Fertilizer - Residue removal rate - Biogenic carbon content Yellow dashed line is the mean. Solid black line is the median. 13

14 Consumptive Water Use Life Cycle Consumptive Water Use (L pe er km traveled) Advanced Corn Grain Dry mill Uncertainty Base case 5th/95th percentile Corn Stover Draft results Switchgrass Biochemical Wheat Straw Forest Residue Thermochemical Uncertainty runs had corn stover and wheat straw irrigation fixed at 0. Several Metrics - GHG emissions - Consumptive water use - Fossil energy demand Gasoline 2005 Parameters with greatest impact across all metrics: - Biomass Yield - Irrigation - Nitrogen Fertilizer - Residue removal rate - Biogenic carbon content 14

15 Key challenges facing the biofuels industry 1. The Blend Wall E10 market will soon be saturated and E85 market is very small and stagnant Even if E15-E25 blends are allowed, market is limited Advanced biofuels one key for expanding markets and achieving societal benefits 2. Developing plausible business cases for producers - Profit, crop insurance, etc 3. Cost Competitive Cellulosic Biofuels Access to capital 4. Sustainability Land use change / availability Water use / water quality GHG / Climate change 15 National 15Renewable Energy Laboratory

16 Conclusions and Gratitude 1. Follow ISO guidelines whenever possible - System expansion if possible, then allocation - Average operations vs. marginal changes (attributional vs. consequential), consider which is most appropriate and if data exists 2. Modern tillage and crop/land management practices can significantly improve sustainability of biofuels 3. Biorefinery process design has a large impact environmental metrics - Utility systems have a huge impact on overall net energy and GHG 4. Uncertainty - Many environmental uncertainties remain - New methods of quantifying Thank you to DOE Office of Biomass Program for support and guidance - Particularly Zia Haq, John Ferrell, Alison Goss-Eng, Valri Lightner, Valerie Sarisky-Reed, Leslie Pezzullo, Paul Grabowski, Johnathan Male, Joyce Yang Thank you also to National Lab and agency partners - ANL, INL, PNNL, ORNL, USDA, EPA, etc. 16

17 Supplemental Information 17

18 Cellulosic Conversion Technology Significantly More Challenging than Conventional Cellulose sugars more tightly bonded than starch Matrix of hemicellulose, cellulose, and lignin polymers Multiple sugars in biomass Feedstock heterogeneity Carpita, N.C. & Gibeaut, D.M Structural models of primary cell walls in flowering plants: consistency of molecular structure with the physical properties of the walls during growth. The Plant Journal 3 (1), 1-30.

19 Analysis Methodology Appropriate Level of Analysis for Project Stage of Development Early Stage: Simple spreadsheet, back of the envelope estimates Mid Stage: Industry-relevant ASPENPlus process simulation Kinetic modeling and regression analysis tools Early Stage: Simple cash flow analysis Mid Stage: Discounted cash flow rate of return analysis R&D Conceptual Process Design Material and Energy Balance Capital and Project Cost Estimates Economic Analysis Environmental / Sustainability Analysis 19

20 Biochemical Conceptual Design Report Drives R&D Direction Enzyme Production (Currently being updated) Pretreatment Conditioning Enzymatic Hydrolysis Co- fermentation ti Product of C5 & C6 Recovery Sugars Ethanol Hybrid Saccharification & Fermentation - HSF Residue Processing By-products Conceptual design of a 2,000 tonnes/day commercial plant one possible tech package, not optimized NREL pilot plant based on this process Basis for connecting R&D targets to cost targets Has undergone rigorous peer review Basis for comparison against other technology options

21 Integrated Biorefinery Research Facility (IBRF) Capabilities / Features Two Parallel (~0.5 ton/day) Pretreatment Processing Trains ~1 ton/day Saccharification / Fermentation Capability Provides Multiple Biomass Pretreatment and Feedstock Options for R&D and Demonstration Support Significantly Improves the Attractiveness, Capability and Probability for Industry Partnerships Flexibility to Meet Industry s Growing Desire for RD&D Partnerships as Market Needs for Biofuels Accelerate National Renewable Energy Laboratory Innovation for for Our Energy Future