assessment: role of e15 in reducing ghg emissions
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Phone (312) 355-3982 ● Fax (312) 996-5620
March 18, 2015 Subject: Role of E15 in Reducing GHG Emissions To Whom it May Concern: Below I am providing a technical assessment of the greenhouse gas (GHG) emissions impact of converting 23.4 billion gallons of E10 gasoline to E15 across a 7 state area. In this analysis I am using the carbon intensity (CI) unit commonly used for life cycle assessments of fuels. The CI of a fuel is generally stated as the mass of carbon dioxide equivalent (including carbon dioxide, nitrous oxide, and methane) emitted per energy unit of fuel. The common unit is gCO2e/MJ. The CI of a fuel is determined by adding the emissions incurred along its production pathway for the product life cycle including fuel feedstock origination (e.g. drilling, mining, corn growing), feedstock conversion at refineries, and combustion in the vehicle. For biofuels, in particular, the land requirements for feedstock production can also produce emissions and/or sequestration effects from carbon stock adjustments. Computable economic equilibrium models are often used to determine land use change (LUC) prompted by biofuels production and the assessed LUC is subsequently multiplied by carbon stock emissions factors specific to ecosystem changes to derive LUC carbon emissions associated with a particular biofuels pathway. New processing technologies as well as updated life cycle models and databases accessed by computable general equilibrium models have significantly advanced the CI assessments of biofuels over the last 10 years. For corn ethanol, for example, the following research updates have occurred:
1) LUC Carbon Emissions
Published studies on LUC emissions have shown a significant reduction in the predicted carbon
emission magnitude over time. This downward trend in predicted emissions is due to several
factors in improved CGE models including 1) an evolving understanding of the elasticity of land
transitions and yield-price relationships, 2) better addressing of ethanol co-product
substitutions in animal feed markets, 3) better understanding and data availability of global land
types, and 4) carbon adjustments during land transitions.
Energy Resources Center (MC 156)
Agriculture and Bioenergy Research Center
1309 South Halsted
Chicago, Illinois 60607-7022
www.erc.uic.edu
Phone (312) 355-3982 ● Fax (312) 996-5620
Figure 1: Predicted Land Use Change Emissions by Different Studies Over Time
2) Technology Innovation at the Biorefinery
The use of fossil energy at the biorefinery is a significant contributor to the CI of ethanol.
Published surveys of the ethanol industry showed that 2008 ethanol plants use 30% less energy
to convert corn to ethanol than 2001-era plants.1 A recent follow up survey showed further
energy reductions.2
3) Technology Innovation in Feedstock Agriculture
Emerging agricultural practices and technologies have been shown to further reduce land
demands and emissions from biofuels production. Most noteworthy are applications of
nitrification inhibitors which stabilize nitrogen fertilizer inputs (a market that has seen 20% year
over year growth for the last 5 years), advanced hybrid seeds, and precision agriculture.
4) Updated Modeling
The Argonne CCLUB greenhouse gas emissions model from biofuels production incorporates
detailed carbon stock factors for different ecosystems that enable an exhaustive analysis of
carbon emissions and sequestration from LUC. For selected modeling runs (that take realistic,
projected crop yield increases into account) the LUC emissions in CCLUB for corn ethanol total 7-
9.0 gCO2e/MJ (as opposed to 28 gCO2e/MJ used by EPA for corn ethanol). 3,4
1 Mueller, S. (2010). 2008 National dry mill corn ethanol survey. Biotechnology Letters, 32, 1261-1264. 2 Mueller, S. and John Kwik. Corn Ethanol: Emerging Plant Energy and Environmental Technologies, 2012, available at
www.erc.uic.edu 3 Ho-Young Kwon, Steffen Mueller, Jennifer B. Dunn, Michelle M. Wander; Modeling state-level soil carbon emission factors
under various scenarios for direct land use change associated with United States biofuel feedstock production; Biomass and
Bioenergy (2013), http://dx.doi.org/10.1016/j.biombioe.2013.02.021 4 Jennifer B Dunn, Steffen Mueller, Ho-young Kwon and Michael Q Wang; Land-use change and greenhouse gas emissions from
corn and cellulosic ethanol; Biotechnology for Biofuels 2013, 6:51 doi:10.1186/1754-6834-6-51; Published: 10 April 2013
Phone (312) 355-3982 ● Fax (312) 996-5620
5) Greenhouse Gas Savings from E15 Sales in the City of Chicago
Recent Argonne GREET life cycle emissions analyses estimate that corn ethanol greenhouse gas emissions are 19-48% (mean=34%) lower than conventional gasoline.5 Each gallon of E15 saves 1.25 gCO2e/MJ over E10 on a life cycle basis. At the modeled conversion of 23.4 billion gallons of E10 gasoline to E15 gasoline the CO2 savings for the seven state area would total 3.41 million metric tonnes CO2e annually. The total CO2 savings from ethanol blended into that fuel supply relative to E0 amount to 9.91 million metric tonnes. If only half of the modeled fuel gallons switch from E10 to E15 then the total savings across the seven state area total 1.71 million metric tonnes. Table 1: Emissions Savings Assuming 100% Transition to E15 Blends6
Gallons
Metric Tonnes CO2e
E10-E15 (100% Switch)
Metric Tonnes CO2e
E0-E15 (100% Switch)
Iowa 1,515,276,000 220,821.62 641,834.72
Illinois 4,553,934,000 663,646 1,928,938
Kansas 1,264,158,000 184,226 535,467
North Carolina 4,239,816,000 617,870 1,795,885
Ohio 4,880,106,000 711,179 2,067,096
Michigan 4,536,126,000 661,051 1,921,395
Wisconsin 2,410,422,000 351,272 1,020,997
Total: 23,399,838,000 3,410,065 9,911,612 Table 2: Emissions Savings Assuming 50% Transition to E15 Blends
Gallons
Metric Tonnes CO2e
E10-E15 (50% Switch)
Iowa 757,638,000 110,411
Illinois 2,276,967,000 331,823
Kansas 632,079,000 92,113
North Carolina 2,119,908,000 308,935
Ohio 2,440,053,000 355,590
Michigan 2,268,063,000 330,525
Wisconsin 1,205,211,000 175,636
Total: 11,699,919,000 1,705,033
5 Wang, M., et al (2012) Well-to-wheels energy use and greenhouse gas emissions of ethanol from corn, sugarcane and cellulosic
biomass for US use. Environ. Res. Lett. 7 045905 6 Gasoline gallons per state provided by Smoot Tewes Group.
Phone (312) 355-3982 ● Fax (312) 996-5620
Table 3: CI of Different Fuels
Finished Gasoline
gCO2/MJ
E15 over E10
Savings
gCO2e/MJ
E15 over E0
Savings
gCO2e/MJ
E15 94.36 1.25 3.64
E10 95.61
E0 98.00 I hope this analysis provides some scientific illumination on this topic. Please do not hesitate to contact me by phone at 312-316-3498 or by email at muellers@uic.edu if you have any further questions. Sincerely,
Steffen Mueller, PhD Principal Research Economist Energy Resources Center Director, Agriculture and Bioenergy Research Center University of Illinois at Chicago
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