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Environmental Impacts of Biofuels: Lifecycle greenhouse gas emissions Mississippi State University January 28 2014

Environmental Impacts of Biofuels: Lifecycle greenhouse gas emissions Mississippi State University January 28 2014. Valerie Thomas School of Industrial and Systems Engineering, and School of Public Policy. Biofuel motivation 1.

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Environmental Impacts of Biofuels: Lifecycle greenhouse gas emissions Mississippi State University January 28 2014

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  1. Environmental Impacts of Biofuels: Lifecycle greenhouse gas emissionsMississippi State UniversityJanuary 28 2014 Valerie Thomas School of Industrial and Systems Engineering, and School of Public Policy

  2. Biofuel motivation 1 Reduce risk of oil embargos, price spikes, geopolitical dependence

  3. Middle East Conflict Six day war - June 5 1967Arab oil embargo - June 6 Yom Kippur War - 1973Arab Oil Embargo - 1973Iranian Revolution - 1979

  4. Crude oil prices since 1861 BP Statistical Review of World Energy 2010

  5. Biofuel motivation 2 Support US farmers Similar motivation for ethanol production from sugar cane in Brazil

  6. Biofuel motivation 3 Reduce greenhouse gas emissions Coal: C135H96O9NS … (or CH for short)Petroleum (octane): C8H18 …Natural Gas (methane): CH4 1 kg C corresponds to 44/12 kg CO2 1 kg uncombusted CH4 corresponds to 25 kg CO2e in 100 year time horizon.

  7. Earth’s Spectrum Shows GHG effects Archer, Chp. 4, Greenhouse Gases

  8. Water is a Greenhouse GasWater Excitation Levels Archer, Chp. 4, Greenhouse Gases

  9. CO2 excitation levels Archer, Chp. 4, Greenhouse Gases

  10. Effectiveness of Greenhouse Gases Depends on Their RadiativeEfficiency and Time Dependent Decay Radiative Efficiency: W/m2/kg Time dependent decay: x(t)

  11. Selected Greenhouse Gases The CO2 response function used in this report is based on the revised version of the Bern Carbon cycle model used in Chapter 10 of this report (Bern2.5CC; Joos et al. 2001) using a background CO2 concentration value of 378 ppm. The decay of a pulse of CO2 with time t is given by where a0 = 0.217, a1 = 0.259, a2 = 0.338, a3 = 0.186, τ1 = 172.9 years, τ2 = 18.51 years, and τ3 = 1.186 years. IPCC 2007

  12. Global Warming Potential TH is time horizon, a is radiative efficiency of increase of one unit of substance (W/m2/kg); x and r are time dependent decay of substance x and reference gas r.

  13. Selected Greenhouse Gases IPCC 2007

  14. Atmospheric CO2 for 400,000 years Carbon dioxide concentrations in Antarctica over 400,000 years. “The graph combines ice core data with recent samples of Antarctic air. The 100,000-year ice age cycle is clearly recognizable.” (Data sources: Petit et al. 1999; Keeling and Whorf 2004; GLOBALVIEW-CO2 2007.)

  15. Anthropogenic Carbon Emissions Boden et al. 2011

  16. Mauna Loa Data Set

  17. Biofuel motivation 3Reduce greenhouse gas emissionsBiomass is often credited with zero greenhouse gas emissions www.wfpa.org

  18. Life Cycle Assessment Assessment of the environmental impacts of a product or service including • raw material extraction, • manufacturing, • distribution, • use, and • end of life.

  19. US Renewable Fuel StandardUS EISA

  20. US Renewable Fuel Stadnard (RFS2)Lifecycle Greenhouse Gas Emissions Requirements Compared to Petroleum Fuels • advanced renewable fuels < 50 % • cellulosic renewable fuels < 40 % • funding for development < 20 %

  21. Lifecycle Energy and GHG Emissions from Ethanol Produced by Algae Ron Chance, Matthew Realff, Valerie Thomas Zushou Hu, DexinLuo, Dong Gu Choi School of Chemical and Biomolecular Engineering, and School of Industrial and Systems Engineering

  22. System Boundary for LCA

  23. LCA Results Depend on Initial Ethanol Concentration

  24. Analysis Framework: Consider Baseline and Two Extensions Baseline Extension 1 Extension 2 • Initial Concentration • 1 wt% • External Energy Supply • CHP+ Natural gas • Heat Exchange Efficiency • 80% • Initial Concentration • 0.5~5.0 wt% • External Energy Supply • CHP + Natural gas • Grid Electricity+ Natural gas • CHP + Solar thermal + Natural gas • Heat Exchange Efficiency • 90% • Initial Concentration • 0.5~5.0 wt% • External Energy Supply • CHP + Natural gas • Grid Electricity+ Natural gas • CHP + Solar thermal + Natural gas • Heat Exchange Efficiency • 80%

  25. Fertilizer Energy and GHG emissions 1 Production Rate Ethanol: 56,000 l/hectare Waste Biomass: 0.97 ton/hectare Algae Composition (1) Energy and GHG emissions Nitrogen: 8 wt% Phosphorous: 0.3wt% Nitrogen: 0.0017 MJ/MJEtOH 0.11 g CO2e/MJEtOH Phosphorous: 0.000017 MJ/ MJEtOH 0.0026 g CO2e/MJEtOH Nitrous Dioxide: 0.1 g CO2e/MJEtOH Fertilizer Parameters (2-3) Nitrogen: 23.7 MJ/kg Nitrogen: 1.675 kg CO2e/kg Phosphorous: 5.78 MJ/kg Phosphorous: 0.97 kg CO2e/kg Nitrous Dioxide: 0.005 g N2O /g N • ECN, Phyllis: The Composition of Biomass and Waste. 2010. http://www.ecn.nl/phyllis/ • Kongshaug, G., Energy consumption and greenhouse gas emissions in fertilizer production. IFA Technical Conference, Marrakech, Morocco, 1998. • US DOE, Agricultural Chemicals: Fertilizers, Energy and Environmental Profile of the U.S. Chemical Industry. Energy and Environmental Profile of the U.S. Chemical Industry, Chapter 5. Technologies, O. o. I. 2000

  26. Bioreactor Production and Disposal 2 Assumptions Photo-bioreactor systems to be replaced every 5 years; No GHG emissions from drained bioreactors; 1 2 Production of Polyethylene (1) Dimension of the PBR Energy use: 76 MJ/kg GHG emissions: 1.9 kg CO2e /kg Length: 50 feet Circumference: 12.6 feet Wall thickness: 5~10 mil Results Energy use: 0.05 MJ/MJEtOH GHG emissions: 1.3 g CO2e/MJEtOH • GREET, ANL

  27. Ethanol Distribution and Combustion Assumptions from GREET Model 3 40% barge: 520 miles 0.54 MJ/ton-mile 40% railroad tanks: 800 miles 0.36 MJ/ton-mile 20% trucks: 80 miles 0.9 MJ/ton-mile 0.0031 g CH4 and 0.0024 g N2O per MJ of ethanol combusted 1 2 3 4 Results Distribution: 0.017 MJ/MJEtOH 1.6 g CO2e/MJEtOH Combustion: 0.84 g CO2e/MJEtOH

  28. Freight Truck Energy Intensity 1 mile = 1.6 km 1 ton = 0.907 tonnes 1 Btu = 1055 J

  29. Air freight energy intensity

  30. Freight energy intensity

  31. CO2 Delivery and Water Consumption Assumptions 4 Source water pumped from a depth of 100 meters; Water is circulated to the power plant 6 km away; Reverse osmosis seawater desalination; (1) No water loss through evaporation. 1 2 3 4 Results Water pumping: 0.002 kWh/MJEtOH Carbonation: 0.00090 kWh/MJEtOH Water consumption 0.926 l/lEtOH Reverse osmosis: 9.5×10-5 kWh/MJEtOH • National Research Council Review of the Desalination and Water Purification Technology Roadmap; Washington, DC, 2004

  32. Ethanol Separation Process 5 6 7

  33. Ethanol Separation Process Compression Energy 5 Processes: Vapor Compression Steam Stripping and Distillation Inputs HYSYS simulation 0.051 MJ/MJEtOH P T Efficiencies 1 2 0.055 MJ/MJEtOH

  34. Ethanol Separation Process Evaporation Energy & Molecular Sieve 6 7 Evaporation Processes: Vapor Compression Steam Stripping Efficiencies Inputs HYSYS simulation 0.16 MJ/MJEtOH heat exchange column eff. wt% T 1 1 2 2 0.17 MJ/MJEtOH • Final Purification Processes: Molecular Sieve • The total heat requirement : 1 ~ 2 MJ/kgEtOH. (1) • In this study : 1.5 MJ/kgEtOH, or 0.056 MJ/MJEtOH (1) Cho, J.; Park, J.; Jeon, J.-k., Comparison of three- and two-column configurations in ethanol dehydration using azeotropic distillation. J. Ind. Eng. Chem. (Seoul, Repub. Korea) 2006, 12 (2), 206-215.

  35. Baseline Energy Use per MJ of Ethanol Produced for Process Steps at 1wt% 1 2 3 4 5 6 7

  36. Baseline GHG Emissions for 1wt% at 80% heat exchange efficiency 1 2 3 4 5 6 7

  37. Baseline GHG Emissions for 1wt% at 80% and 90% heat exchange efficiency 1 2 3 4 5 6 7

  38. External Energy Supply Scenarios S1 • Electrical energy • U.S. grid electricity 700 g CO2e/kWhe • Process heat • Natural gas 50.38 g CO2e/MJEtOH S2 • Electrical energy and heat • Natural gas fueled CHP 478 g CO2e/kWhe • Extra Process heat • Natural gas 50.38 g CO2e/MJEtOH S3 • Electrical energy and heat • Natural gas fueled CHP 478 g CO2e/kWhe • Process heat • 14 hr Natural gas 50.38 g CO2e/MJEtOH • 10 hr Solar thermal 0g CO2e/MJEtOH

  39. Lifecycle GHG Emissions for 80% and 90% heat exchange efficiencies 0.5wt%~5wt% g CO2e/MJ Ethanol DOE target of 40% of the gasoline emission DOE target of 20% of the gasoline emission Ethanol wt % from phtobioreactors

  40. Life Cycle Inventory Assessment How does the ethanol concentration and mix of fuels to generate heat and power influence the ability of the system to meet RFS? Natural Gas + US Grid Natural Gas CHP + Solar Thermal Natural Gas CHP

  41. Conclusion and Discussion • DOE 40% goal (36.5 g CO2e/MJEtOH) achievable by all three energy supply scenarios and initial concentration as low as 0.5% • DOE 20% goal (18.3 g CO2e/MJEtOH) more challenging • Advantage 1: the potential to locate production facilities on low-value, arid, non-agricultural land, and the resulting avoidance of competition with agriculture • Advantage 2: no-harvest strategy has the potential for more energy efficient separations, lower fertilizer requirements, and lower water usage in comparison to other algae biofuel processes. • Technical challenge: the algae- produced ethanol system does not produce extra biomass waste that can be used as energy to power the process

  42. Does making ethanol use more fossil energy and release more greenhouse gases than the gasoline it is designed to replace? Farrell et al. 2006. Ethanol Can Contribute to Energy and Environmental Goals. Science311:506.

  43. Sources of biomass carbon emissions • Production, transport use fossil fuel • Soil carbonloss (direct or indirect) • Regeneration time

  44. Sample Bioenergy Lifecycle CO2e Emissions Thomas and Liu 2013

  45. Assessment of Alternative Fibers Valerie Thomas, Wenman Liu, Norman Marsolan Institute for Paper Science and Technology School of Industrial and Systems Engineering School of Public Policy Georgia Institute of Technology

  46. Arundodonax Perennial Grown for bioenergy High yield Low input Invasiveness

  47. Kenaf Annual Grown for fiber Medium yield Low input

  48. Bamboo Perennial Widely grown in China High yield Low input Invasiveness

  49. Wheat Straw Agricultural residue No additional: - land use - fertilizers - pesticides - irrigation

  50. Northern softwood Biodiversity Carbon storage Low input Bamboo as alternative

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