Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard
The U.S. Energy Independence and Security Act of 2007 (EISA, P.L. 110-140), significantly expanded the renewable fuel standard (RFS) established in the U.S. Energy Policy Act of 2005 (EPAct 2005, P.L. 109-58). The RFS requires the use of 9.0 billion gallons of renewable fuel in 2008, increasing to 36 billion gallons in 2022. Further, EISA requires an increasing amount of the mandate be met with “advanced biofuels”—biofuels produced from feedstocks other than corn starch and with 50% lower lifecycle greenhouse gas emissions than petroleum fuels. Within the advanced biofuel mandate, there are specific carve-outs for cellulosic biofuels and biomass-based diesel substitutes (e.g., biodiesel).
To classify biofuels under the RFS, the U.S. Environmental Protection Agency (EPA) was directed to calculate the lifecycle emissions of each fuel relative to gasoline or diesel fuel. Lifecycle emissions include emissions from all stages of fuel production and use (“well-to-wheels”), as well as both direct and indirect changes in land use from farming crops to produce biofuels. Debate is ongoing on how each factor in the biofuels lifecycle should be addressed, and the issues surrounding direct and indirect land use are particularly controversial. How EPA resolves those issues will affect the role each fuel plays in the RFS.
EPA issued a Notice of Proposed Rulemaking on May 26, 2009, for the RFS with suggested methodology for the lifecycle emissions analysis. EPA is expected to promulgate regulations on biofuels lifecycle emissions in the next few months, although this rulemaking is already overdue under EISA. As EPA’s decisions will affect the marketability of each combination of fuel type, feedstock, and production process, there is growing congressional interest in the topic. Congressional action could take the form of oversight of EPA’s rulemaking process, or could result in legislation to amend the EISA RFS provisions. Further, related legislative efforts on climate change policy and/or a low-carbon fuel standard would likely lead to interactions between those policies and the lifecycle determinations under the RFS.
Contents
Introduction
On August 8, 2005, President Bush signed the U.S. Energy Policy Act of 2005 (EPAct 2005, P.L. 109- 58). Among other provisions, EPAct 2005 established a renewable fuel standard (RFS) requiring gasoline to contain a minimum amount of fuel produced from renewable biomass. Through 2007 the requirement was largely met using corn-based ethanol,{[ref|1}} although other fuels such as biodiesel played a limited role.{[ref|2}} The law directed EPA to establish a credit trading system to provide flexibility to fuel producers; ethanol produced from cellulosic feedstocks was granted extra credit. Also, P.L. 109-58 required that a relatively small amount (250 million gallons, or roughly 0.2% of gasoline consumption) of cellulosic ethanol be blended in gasoline annually starting in 2013.{[ref|3}} The U.S. Energy Independence and Security Act of 2007 (EISA, P.L. 110-140), signed by President Bush on December 19, 2007, significantly expanded the RFS to include all transportation fuels and heating oil, requiring the use of 9.0 billion gallons of renewable fuel in 2008, increasing to 36 billion gallons in 2022. These mandates represent roughly 5% and 18% of motor fuel consumption by volume, respectively. EISA also requires an increasing amount of the mandate be met with “advanced biofuels”—biofuels produced from feedstocks other than corn starch and with 50% lower lifecycle greenhouse gas emissions{[ref|4}} than petroleum fuels. Within the advanced biofuel mandate, there are specific carve-outs for cellulosic biofuels and biomass-based diesel substitutes (e.g., biodiesel). Under EPAct 2005, the Environmental Protection Agency (EPA) released a final rulemaking for 2007 and beyond. Included in the rule were provisions for credit trading, as well as for generating credits from the sale of biodiesel and other fuels.{[ref|5}} Because of the changes in the RFS from P.L. 110-140, EPA is required to publish new rules to reflect those changes. Perhaps most importantly, EPA will need to develop rules for determining the lifecycle greenhouse gas emissions from renewable fuels. EPA issued a Notice of Proposed Rulemaking for the RFS with suggested methodology for the lifecycle greenhouse gas emissions analysis.{[ref|6}} Fuels from new biorefineries (i.e., excluding existing corn ethanol plants) must achieve at least a 20% lifecycle greenhouse gas reduction relative to petroleum fuels, and advanced biofuels (i.e., fuels other than corn ethanol) must achieve at least a 50% reduction, with cellulosic biofuels needing a 60% reduction. As there are specific carve-outs for certain fuels, how each fuel is defined will have direct effects on the application of that fuel under the RFS. For example, whether sugar-based ethanol from Brazil (Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard) is classified as an advanced biofuel or a conventional biofuel will determine whether it must compete with less expensive corn-based ethanol from the Midwest or with more expensive advanced biofuels (see Figure 1). If it were determined that, for example, Brazilian sugar ethanol does not achieve the 50% reduction necessary for advanced biofuels, then it could only qualify as part of the overall RFS, as opposed to the advanced biofuel carve-out. Likewise, if corn ethanol were found to not achieve the necessary 20% reduction in lifecycle emissions, then ethanol from new corn-based biorefineries would not qualify for inclusion in the RFS, while fuel from plants that began construction before December 19, 2007 is grandfathered under the law.{[ref|7}}
To classify biofuels under the RFS, EPA must calculate the lifecycle emissions of each fuel relative to gasoline or diesel fuel. Debate is ongoing on how each factor in the biofuels lifecycle should be addressed, and the issues surrounding direct and indirect land use are particularly controversial. How EPA resolves those issues will affect the role each fuel plays in the RFS.
RFS Requirements
Volume Requirements
Under EISA, the RFS requires the use of just over 11 billion gallons of renewable fuel in 2009, increasing to 36 billion gallons by 2022 (see Table 1). Within that mandate, there is a specific carve-out for advanced biofuels, increasing from 0.6 billion gallons in 2009 to 21 billion gallons by 2022. The remaining share of the RFS, which is capped at 15 billion gallons by 2015, will likely be met using corn-based ethanol, although there is no specific carve-out for that fuel (see Figure 2).
Table 1. Expanded Renewable Fuel Standard Requirements Under P.L. 110-140 Advanced Biofuels Year Total RFS Mandate (billion gallons) Total Advanced Biofuel Mandate (billion gallons)a Cellulosic Biofuel Mandate (billion gallons)b Biomass-Based Diesel Fuel (billion gallons)b Unspecified (Effective Cap on Corn Ethanol)c 2006 2007 2008 9.0 9.0 2009 11.1 0.6 0.5 10.5 2010 12.95 0.95 0.1 0.65 12.0 2011 13.95 1.35 0.25 0.8 12.6 2012 15.2 2.0 0.5 1.0 13.2 2013 16.55 2.75 1.0 1.0 13.8 2014 18.15 3.75 1.75 1.0 14.4 2015 20.5 5.5 3.0 1.0 15.0 2016 22.25 7.25 4.25 1.0 15.0 2017 24.0 9.0 5.5 1.0 15.0 2018 26.0 11.0 7.0 1.0 15.0 2019 28.0 13.0 8.5 1.0 15.0 2020 30.0 15.0 10.5 1.0 15.0 2021 33.0 18.0 13.5 1.0 15.0 2022 36.0 21.0 16.0 1.0 15.0 Source: CRS analysis of P.L. 110-140 a.
The advanced biofuel (i.e., non-corn-starch ethanol) mandate is a subset of the RFS. The difference between the RFS mandate and the advanced biofuel mandate—15 billion gallons in 2015 onward) is effectively a cap on corn ethanol under the program. b. The cellulosic biofuel and biomass-based diesel fuel mandates are subsets of the advanced biofuel mandate. c. Although this portion is sometimes referred to as a carve-out for corn-based ethanol, in fact any qualified renewable fuel may be used to meet this portion of the mandate. Therefore, this portion of the RFS effectively establishes a cap on corn ethanol under the RFS, while the actual amount of corn ethanol could be lower. Figure 2. Renewable Fuel Standard Under EISA, by Year Source: CRS Analysis of P.L. 110-140. Within the advanced biofuel carve-out, there are specific carve-outs for biofuels produced from cellulosic materials (e.g. perennial grasses, fast-growing trees){[ref|8}} and for biomass-based diesel substitutes. The remaining share of the advanced biofuel mandate is unspecified and could potentially be met using sugar-based ethanol or other biofuels (see Figure 3). Figure 3. Advanced Biofuels Carve-Outs Under EISA, by Year Source: CRS Analysis of P.L. 110-140. (Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard)
Lifecycle Requirements
To be classified as advanced biofuel, biomass-based diesel fuel, or cellulosic biofuel under the RFS, fuels must have lower lifecycle emissions relative to petroleum products (see Table 2). Further, conventional biofuels produced from new biorefineries must have 20% lower lifecycle emissions than petroleum products.
Table 2. Lifecycle Emissions Reductions for Specified Biofuels Under the RFS Reductions Relative to Petroleum Fuels Advanced Biofuels Conventional Biofuels from New Biorefineriesa Unspecified Advanced Biofuels Biomass-Based Diesel Substitutes Cellulosic Biofuels 20% 50% 50% 60% Source: CRS Analysis of P.L. 110-140. a. Facilities that began construction after December 19, 2007. Conventional biofuels from facilities that began construction before that date are subject to no lifecycle emissions requirements. Under the definition of lifecycle greenhouse gas emissions under Section 201 of EISA, EPA must consider all significant emissions, both direct and indirect, from a wide array of fuels and feedstocks. {[ref|9}} Therefore, the potential number of variables EPA will need to consider is high, as will be discussed below. Further, EISA does not specify the methodology for EPA to make its determinations on lifecycle emissions. Thus, EPA will also need to develop the methodology for that analysis. The recommended methodology EPA put forth in its notice of proposed rulemaking is described in a subsequent section of this report. Section 202 of EISA directs the EPA Administrator to revise the RFS regulations no later than one year after enactment (December 19, 2008). However, this deadline has since passed, and it is unclear when a proposed or final rule on biofuels lifecycle emissions will be issued by the Agency.{[ref|10}} (Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard)
Lifecycle Analysis
Estimations of the greenhouse gas emissions attributable to a fuel require detailed analysis of three key components: 1) the processes required to produce feedstocks, convert them into fuel, and deliver the fuel to the end-user; 2) the emissions from the vehicle itself; and 3) any direct or indirect changes in emissions not attributable to fuel production or use, including changes in land use. The first two components are often referred to as “well-to-tank” and “tank-to-wheels” emissions; both taken together are referred to as “well-to-wheels” emissions. Figure 4 shows some of the main elements of the biofuels life cycle.
Well-to-Tank
There are many steps in producing and delivering fuel to an end-user. For gasoline, these steps include—but are not necessarily limited to—extraction of crude oil, crude oil transport, refining, gasoline transport, and delivery. For corn ethanol, these steps include corn production, harvesting, and transport; corn processing and ethanol distillation; and transport and delivery. Each of these larger steps can be broken down into smaller pieces, each of which requires energy and produces greenhouse gas emissions. For example, in the case of corn production, energy is required to operate machinery and to produce fertilizers.{[[Further, greenhouse gases are released from the application of nitrogen-based fertilizers, and from other agricultural operations. Varying assumptions of which inputs are relevant can lead to a wide range in total energy requirements, and thus, greenhouse gas emissions. Further, different assumptions about factors such as resource use, process efficiency, production yields, and the role of co-products (e.g., animal feed) can also lead to differences in emissions estimates.
Tank-to-Wheels
The emissions from the end use of the fuel (“tank-to-wheels”) are easier to quantify. Assuming the carbon content of the fuel is known, then taking a given rate of consumption (the vehicle’s fuel economy), estimates of carbon dioxide emissions can be calculated. Added to these are the expected emissions of any non-CO2 greenhouse gases (e.g., methane, [../154865/index.html nitrous oxide]]).
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For petroleum fuels, potential lifecycle emissions include the following sources:
For ethanol, potential lifecycle emissions include the following sources:
Sources: Jason Hill, Stephen Polasky, and Erik Nelson, et al., “Climate Change and Health Costs of Air Emissions From Biofuels and Gasoline," Proceedings of the National Academy of Sciences, vol. 106, no. 6 (February 10, 2009), p. 2082. U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Biomass Program, Ethanol: The Complete Lifecycle Energy Picture, March 2007, http://www1.eere.energy.gov/ vehiclesandfuels/pdfs/program/ethanol_brochure_color.pdf. |
Land Use Change
Arguably, the most difficult variable to quantify in assessing fuel lifecycle emissions is the role of land use change. Land is a requisite input to grow feedstock for biofuel production. Some contend that significant land use change, both direct and indirect, will occur to accommodate annual RFS requirements. Inclusion and measurement of greenhouse gas emissions associated with direct and indirect land use change happening as a result of a burgeoning biofuels market is a pressing concern.
Particular attention is being paid to the carbon debt{[ref|12}} brought about from land use change to accommodate biofuel feedstock production. Including the carbon debt may lessen the emission reduction ability of said biofuels. Measurement techniques to quantify, verify and monitor the carbon debt rely on the robustness of land use data sets and land use change models.
Controversy Over Biofuels Lifecycle Analysis
The biofuels lifecycle analysis has placed scientists, environmentalists, industry representatives, and policy makers in a quandary. The lack of a precedent by which interested groups can seek guidance further complicates matters. Apprehension exists mainly regarding the land use components within the analysis and sound measurement techniques to accurately quantify the land use components. Currently, EISA (P.L. 110-140) requires EPA to account for greenhouse gas emissions from both direct and indirect land use change. As such, major implications may arise concerning the type and quantity of biofuels produced to meet RFS requirements. Some researchers argue that greenhouse gas emissions from land use change are not accounted for in biofuel production estimates.{[ref|13}} If so, crop-based biofuel production may result in larger quantities of greenhouse gas emissions than previously thought. Biofuels developed from agricultural and crop waste may not be subject to the additional greenhouse gas emissions from land use change, direct or indirect.
Indirect land use change (ILUC) involves the greenhouse gas emission estimation of land cleared or converted for crop production by entities other than the feedstock producer, including the conversion of land in foreign countries. Some argue any ruling issued by the EPA that consists of ILUC is premature as the predicted impacts may be based on models using incomplete data sets, and assumptions and calculations that may not be based on sound scientific methodology or observations.
Some biofuels supporters contend that EPA may want to be mindful of the barriers to biofuel generation and use as the Agency implements the statutory language to account for indirect land use change in the biofuel lifecycle analysis. There may be a substantial decrease in the continued development of second-generation advanced biofuels. Innovators may be drawn away from further exploration and refinement of second-generation advanced biofuels if monetary supplements or fuel credits are not granted due to a poor biofuel lifecycle analysis score.
Land use change is a relatively new subject area for researchers to simulate real-world conditions using models, economic or spatial. The certainty of simulation models for land use change compared to real world action is subject to various human and economic considerations. Quantification of greenhouse gas emissions associated with land cover and land use change are contingent upon reliable land use and land cover measurements. Techniques to quantify, verify and monitor emissions from land use change rely on the robustness of land use change prediction methods. Forecasting land use change - specifically conversions as a consequence of the RFS program - may prove challenging. Computer models and satellite imagery can assist decision makers with identifying land areas ideally suited for conversion assuming current land use data sets are acquired on a recurring basis.
However, the development of land-use change estimates is complicated, and the methodology for determining the greenhouse gas impacts of indirect land-use change is in the very early stages of development. According to the Roundtable on Sustainable Biofuels (RSB),
It is difficult to link direct causality of land use changes in one region or country to biofuel production in another. Nevertheless, the potential for negative indirect impacts is high, and within the spirit of the Precautionary Principle, sustainable biofuel supporters should be assured that their good intentions do not have unintended consequences.{[ref|14}}
According to a group of biofuels experts cited by the RSB,
addressing indirect impacts explicitly requires: continued global research to identify and quantify links between biofuels and land use change; mechanisms to promote biofuels that do not have negative land use change impacts; mechanisms that mitigate these negative impacts but do not unduly increase transaction costs for consumers; and social safeguards at the national level, that ensure that vulnerable people are not further disadvantaged through food and energy price increases and other potential negative economic side effects.{[ref|15}}
Models to predict indirect land use change are essentially economic models, as they aim to predict the macroeconomic effects of any direct changes in land use. Critics are concerned that including indirect land use change in such accounting could make biofuel feedstock producers liable for decisions made by actors they can not control, including potentially their competitors. Ultimately, how EPA certifies each combination of fuel type, feedstock, and production processes will directly affect the marketability of that fuel.
Proposed Land Use Change Estimations for the Lifecycle Emissions Analysis
On May 26, 2009, EPA issued a Notice of Proposed Rulemaking (NOPR) to address changes to the RFS. The NOPR includes suggested methodology for a lifecycle analysis of significant greenhouse gas emissions—both direct and indirect—from the production of renewable fuels. Under the NOPR, the lifecycle analysis (LCA) would be conducted to ensure that fuels from new biorefineries (i.e., excluding existing corn ethanol plants) achieve a 20% lifecycle greenhouse gas reduction relative to petroleum fuels, and that advanced biofuels (i.e., fuels other than corn ethanol) and cellulosic biofuels achieve at least a 50% and 60% reduction, respectively. A penalty (e.g., failure to earn credits for RFS credit trading) could be imposed on those renewable fuels that do not meet the specified emission reduction threshold according to the proposed methodology. The following paragraphs summarize the major points of the methodology put forth by EPA in its Notice of Proposed Rulemaking to account for land use change in the LCA.
EPA has identified two criteria most likely to affect the LCA methodology: secondary agricultural sector GHG impacts from increased biofuel feedstock production, and international impact of land use change from increased biofuel feedstock production. Land use change is considered by many to be the most pressing concern.{[ref|16}} Various entities have expressed an opinion about the inclusion of land use change in the LCA, and how to account for its impact. Some contend that robust methods to evaluate domestic land use change should be well understood before incorporating international land use estimates. Some also argue that it is unfair to penalize agricultural producers and biofuel production entities because of land use change that may or may not occur in a foreign territory. EPA representatives have expressed on multiple occasions that, while recognizing that land use change analysis is an emerging science, they are required to proceed with implementing the law.
EPA proposes to use two models, imagery data, and emission factors to estimate GHG emissions associated with land use change for the LCA (see Figure 5).{[ref|17}} Models are employed because resources to monitor and analyze land use change are limited. A single cohesive model or data source to estimate GHG emissions from land use change for the LCA does not exist. The models and data sources will give an assessment of the amount of land converted, the type of land converted, location for the land conversion, and GHG emissions associated with land use change (see Table 3).
Table 3. Land Use Change Methodology Key Issue Domestic Agriculture International Agriculture Amount, or area, of land converted FASOM (domestic agricultural sector model) CARD/FAPRI (international agricultural sector model) Location of land use changes FASOM (regional-level) CARD/FAPRI (country level) Land types, or biomes, converted FASOM (modeled interactions with cropland, pasture, CRP and forest) MODIS Satellite Data (recent trends of land conversion between different land types) GHG emissions from land conversion FASOM (e.g., DAYCENT for soil carbon changes) Winrock/IPCC Source: U.S. Department of Agriculture (USDA) Agricultural Air Quality Task Force May 2009 Meeting. Adapted by CRS. Notes: Forest and Agricultural Sector Optimization Model (FASOM); Center for Agricultural and Rural Development (CARD); Food and Agricultural Policy Research Institute (FAPRI) model; Moderate Resolution Imaging Spectoradiometer (MODIS); Intergovernmental Panel on Climate Change (IPCC); Daily Century model (Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard) (DAYCENT).
EPA’s analysis indicates that the largest release of GHG emissions from biofuel production occurs during the first few years immediately following land conversion. Lower GHG emissions are released in subsequent years of biofuel production. EPA proposes a time horizon as part of its methodology to denote the length of time emissions from land use conversion will be included in the LCA. Time horizon is defined as the time period for which biofuel production is projected to occur. Additionally, EPA proposes to discount emissions to place a value on near-term emissions, which may be estimated with more certainty than long-term emissions. The suggested methodology test would use a 100-year time horizon with 0% discount rate and a 30-year time horizon with a 2% discount rate.
While using some of the best data and models available, EPA appears to recognize that some uncertainty exists regarding the proposed methodology to assess international GHG emissions form land use change. EPA acknowledges that a transparent and scientific analysis of the GHG emission impact of renewable fuels going forward will be further refined as additional data sources and models become available. EPA is seeking peer review and public comment regarding:{[[use of satellite data to project future type of land use changes;
- land conversion GHG emissions factors estimates EPA used for different types of land use;
- estimates of GHG emissions from foreign crop production;
- methods to account for the variable timing of GHG emissions; and
- how the several models EPA relied upon are used together to provide overall lifecycle GHG estimates.
Congressional Role
The 111th Congress will likely address issues surrounding biofuels lifecycle in two ways: 1) oversight of EPA’s implementation of the RFS; and 2) integration of fuel lifecycle emissions into other relevant legislation.
Oversight
Definitions for various biofuels under the RFS could directly affect the supply of eligible fuels in the program. If supply is curtailed through the exclusion of certain fuels,{[ref|19}} then consumer fuel prices could increase. Thus, Congress may look to determine whether any regulations promulgated by EPA adversely affect fuel supply and availability. Likewise, Congress may look to determine whether the goal of reducing greenhouse gas emissions is achieved through the lifecycle requirements of the RFS.
Related Legislation
The 111th Congress is likely to consider legislation to address climate change and energy issues. Transportation plays a key role in both U.S. energy consumption and U.S. greenhouse gas emissions. Therefore, any policy to address these issues will almost certainly affect the implementation of the renewable fuel standard, and vice versa. Specific proposals include a carbon tax or a cap-and-trade system that would put a price on carbon emissions, promoting a switch to lower-carbon fuels; and a low-carbon fuel standard, which would require lower carbon emissions from all transportation fuels (as opposed to just biofuels).{[ref|20}} The specifics of any new legislation on fuel carbon emissions would determine how that legislation interacts with the RFS requirements. New legislation could be integrated with the RFS requirements, or it could lead to competing, or even contradictory, requirements. Therefore, the integration of the RFS with any potential climate or energy policy should be considered.
Reference
- [index.html#ref_1 ^]]</cite>For more information on ethanol, see CRS Report RL33290, Fuel Ethanol: Background and Public Policy Issues, by Brent D. Yacobucci.
- ^Biodiesel is a synthetic diesel fuel made from oils such as soybean oil. For more information, see CRS Report RS21563, Biodiesel Fuel and U.S. Agriculture, by Randy Schnepf.
- ^Currently, world production of cellulosic ethanol is limited. No commercial-scale plants have been completed in the United States, although some demonstration-scale plants have begun producing fuel.
- ^Lifecycle emissions include emissions from all stages of fuel production and use (“well-to-wheels”), as well as both direct and indirect changes in land use from farming crops to produce biofuels.
- ^Environmental Protection Agency, “Regulation of Fuels and Fuel Additives: Renewable Fuel Standard Program, Final Rule,” 72 Federal Register 23899-23948, May 1, 2007.
- ^Environmental Protection Agency, “Regulation of Fuels and Fuel Additives: Changes to Renewable Fuel Standard Program,” 74 Federal Register 24904-25143, May 26, 2009.
- ^Fuels that do not meet the stipulations of the RFS are not banned from sale or use in the United States, but they will not qualify for credits under the RFS. However, as the RFS mandates are significantly higher than expected U.S. biofuels demand in the absence of the mandates, it is likely that exclusion from the RFS will effectively be a barrier to entry into the marketplace. Qualification under the RFS has no bearing on whether fuels qualify for federal tax incentives. For example, if in 2009, ethanol consumption reached 12 billion gallons, only 10.5 billion gallons could be counted toward the RFS; the full 12 billion gallons, however, would be eligible for the ethanol blender’s tax credit. Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard
- ^For more information on cellulosic biofuels, see CRS Report RL34738, Cellulosic Biofuels: Analysis of Policy Issues for Congress, by Tom Capehart.
- ^Section 201 of EISA defines lifecycle emissions as follows: “(H) LIFECYCLE GREENHOUSE GAS EMISSIONS.—The term ‘lifecycle greenhouse gas emissions’ means the aggregate quantity of greenhouse gas emissions (including direct emissions and significant indirect emissions such as significant emissions from land use changes), as determined by the Administrator, related to the full fuel lifecycle, including all stages of fuel and feedstock production and distribution, from feedstock generation or extraction through the distribution and delivery and use of the finished fuel to the ultimate consumer, where the mass values for all greenhouse gases are adjusted to account for their relative global warming potential.” 42 U.S.C. §7545(o)(1).
- ^Press reports indicated that a proposed rule was completed by EPA and forwarded to the Office of Management and Budget (OMB) for review by the Bush Administration in Fall 2008. Later reports indicated that the proposal was been returned to EPA for further consideration. The most recent press reports indicate that the proposed is once again at OMB, and could be issued early in April 2009. Ben German, “Biofuels: EPA Weighs Changes to Proposed RFS Rule’s Emissions Provision,” Greenwire, February 24, 2009; “Administration Eyes ANPR To Defer Fight On RFS Lifecycle Methodology,” EnergyWashington Week, January 6, 2009.
- ^Some analyses include the energy required to produce the machinery, and to feed farm workers.
- ^Joseph Fargione, Jason Hill, and David Tilman, et al., “Land clearing and the biofuel carbon debt,” Science, vol. 319 (February 29, 2008). Fargione et al. define carbon debt as the amount of CO2 released during the first 50 years after the natural environment is converted to cropland.
- ^Timothy Searchinger, Ralph Heimlich, and R.A. Houghton, et al., “Use of U.S. cropland for biofuels increases greenhouse gases through emissions from land-use change,” Science, vol. 319 (February 29, 2008).
- ^Roundtable on Sustainable Biofuels, Global Principles and Criteria for Sustainable Biofuels Production, Version Zero, Lausanne, Switzerland, April 13, 2008, p. 4.
- ^Ibid.
- ^See the “Land Use Change” and “Controversy Over Biofuels Lifecycle Analysis” sections in this report for further explanation regarding the complexity of quantifying land use change for the LCA
- ^Models include the Forest and Agricultural Sector Optimization Model (FASOM) model and the Food and Agricultural Policy Research Institute (FAPRI) modeling system. Imagery data will be obtained from the Moderate Resolution Imaging Spectoradiometer (MODIS) satellite. Winrock emission factor data is proposed for use in estimating international GHG emissions from land types.
- ^Comments are generally accepted until 60 days after notice publication in the Federal Register.
- ^Biofuel supply is largely associated with eligible biomass feedstocks. More than a dozen biomass definitions are included in recent legislation impacting feedstock development assistance available.
- ^For more information on a low-carbon fuel standard (LCFS), see CRS Report R40078, A Low Carbon Fuel Standard: State and Federal Legislation and Regulations, by Brent D. Yacobucci.
Note: The first version of this article was drawn from Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard by Brent D. Yacobucci and Kelsi S. Bracmort, Congressional Research Service, June 25, 2009.
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(2011). Calculation of Lifecycle Greenhouse Gas Emissions for the Renewable Fuel Standard. Retrieved from http://editors.eol.org/eoearth/wiki/Calculation_of_Lifecycle_Greenhouse_Gas_Emissions_for_the_Renewable_Fuel_Standard
