Session 17 ic2011 gustafson
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Session 17 ic2011 gustafson

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Session 17 ic2011 gustafson Session 17 ic2011 gustafson Presentation Transcript

  • Life Cycle Assessment (LCA) ofEthanol Fuel from Willow Biomass Mohit Rastogi, Rick Gustafson, Joyce Cooper, Timothy Volk, Jesse Caputo, Leonard Johnson, Maureen Puettmann CORRIM
  • CORRIM Biofuels Research• Pyrolysis Pyrolysis Oil• Gasification Ethanol • Bioconversion
  • Research objectives Perform LCA on Willow-based Ethanol fuel to evaluate the following: • Global warming potential (GWP) • Fossil energy use • Water use • Other impacts such, toxicity, acidification, and photochemical-oxidants formation To improve the environmental fuel’s performance with contributional analysis.
  • ScopeBiomass production Biomass transport Biochemical conversion (core process)Fuel distribution Fuel use
  • Key assumptions Land use does not cause direct or indirect greenhouse gas emissions. • Direct emissions for site preparation are offset by below ground accumulation. • Use of idle land minimizes indirect land use Feedstock and final products are transported 100 miles (average round trip). Electricity from biorefinery displaces production from US national grid – no regional specificity. Gypsum is disposed of as a solid by-product Comparisons with gasoline are on an equivalent energy (MJ) basis System expansion used to model impacts of co-products
  • Willow Biomass Production Cycle Three-year old after Site Preparation coppicePlanting One-year old after coppice CoppiceFirst year growth Early spring after coppicing
  • Willow Production & Harvesting  The largest inputs in terms of energy and dollars are:  harvesting  site preparation and establishment  N fertilizer inputs  Crop is not irrigated  Willow harvested using single pass cut and chip system  Chips are blown into a forage or dump wagon and sent right to the biorefinery
  • Biochemical conversion process SO2 Steam Lime H2SO4 Gypsum Nutrition(462,000 ton/year) Enzyme Feedstock (Willow) Feedstock storage & Pretreatment and Saccharification & Handling Conditioning Co-Fermentation Recycle water Recycle condensate Steam Steam Broth Nutrition Vent Excess condensate Wastewater Product purification Treatment Still solids and evaporator syrup Ethanol (34 MGPY) Cooling Boiler Steam tower blowdown Burner/Boiler/ Storage blowdown Turbogenerator n Anaerobic, CH4 Utilities (Excess electricity: Electricity ~ 20 MW)
  • Process area Process Yields Value Unit Pretreatment Xylan to Xylose Yield 75 % Mannan to Mannose Yield 61 % Galactan to Galactose Yield 61 % Arabinan to Arabinose Yield 75 % Saccharification Cellulose to Glucose Yield 75 % Co-Fermentation Glucose to Ethanol Yield 95 % Xylose to Ethanol Yield 85 % Arabinose to Ethanol Yield 85 % Mannose to Ethanol Yield 95 % Galactose to Ethanol Yield 95 % Contamination Loss 3 %Overall Yield = 74 gallons ethanol/ton (OD biomass)
  • MethodologyBiomass SimaPro LCAgrowth/yield model GREET vehicle-use(by CORRIM) model (by UW) model (by ANL) ASPEN process model (by NREL and UW)
  • RESULTS
  • Global Warming Potential (GWP)
  • Water use
  • Fossil energy use
  • Other Impacts
  • Conclusions Production of ethanol from willow plantations is near carbon neutral • Displacement of power production from coal and oil • No accounting for indirect land use Water usage for bioconversion is substantial and will need to be addressed Other impacts are mixed –much greater for ethanol (acidification) for some and greater for petroleum(toxicity) for others
  • AcknowledgementThe support for this research from the US Forest Service andthe Department of Energy is greatly appreciated.
  • Willow – excellent feedstock for bioconversion processes Example SRWC (Short Rotation Woody Crop) Rapid early growth rates Ease of vegetative propagation from dormant cuttings. Ability to re-sprout after multiple harvests. Suitable for cultivation on low quality land. Broad genetic diversity Good “sugar release”
  • Agrochemical Combustion CO2 Offgas emissions emissionsSYSTEMBOUNDARIES Fossil fuels production S1: Willow production and collection subsystem Lubricants production Planting Harvesting Chipping Fertilizers production CO2 Pesticides production S2: Ethanol biorefinery subsystem Water Willow chips Gypsum Landfill Feedstock handling Pretreatment & Conditioning Distillation & Dehydration Chemicals production Syrup & solid residues Saccharification & Co-fermentation Ethanol Enzyme production Storage Wastewater treatment conditioning Sludge & biogas Nutrients production Energy production Electricity Steam Utilities Avoided US mix electricity production Landfill Excess electricity Ash S3: Ethanol distribution S4: Ethanol use subsystem Fossil fuels production subsystem
  • Contribution analysis for Ethanol (Other Impacts)