Regulatory Announcement

EPA Lifecycle Analysis of Greenhouse 

Gas Emissions from Renewable Fuels 

Background

As part of revisions to the National Renewable Fuel Standard program (commonly 

known as the RFS program) as mandated in the Energy Independence and Security 

Act of 2007 (EISA), EPA has analyzed lifecycle greenhouse gas (GHG) emissions 

from increased renewable fuels use. EISA established eligibility requirements for 

renewable fuels, including the first U.S. mandatory lifecycle GHG reduction thresholds, 

which determine compliance with four renewable fuel categories. The regulatory 

purpose of EPA’s lifecycle GHG emissions analysis is therefore to determine whether 

renewable fuels produced under varying conditions meet the GHG thresholds for the 

different categories of renewable fuel. Determining compliance with the thresholds 

requires a comprehensive evaluation of renewable fuels, as well as of gasoline and 

diesel, on the basis of their lifecycle emissions.

EISA defines lifecycle GHG emissions as follows: 

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.1

EISA established specific lifecycle GHG emission thresholds for each of four types 

of renewable fuels, requiring a percentage improvement compared to lifecycle GHG 

emissions for gasoline or diesel (whichever is being replaced by the renewable fuel) 

sold or distributed as transportation fuel in 2005. EISA required a 20% reduction 

in lifecycle GHG emissions for any renewable fuel produced at new facilities (those 

1

 Clean Air Act Section 211(o)(1)

Office of Transportation and Air Quality

EPA-420-F-10-006

February 2010
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constructed after enactment), a 50% reduction in order to be classified as biomass-based diesel or 

advanced biofuel, and a 60% reduction in order to be classified as cellulosic biofuel. 

Threshold Determinations

EPA is making threshold determinations based on a methodology that includes an analysis of 

the full lifecycle of various fuels, including emissions from international land-use changes resulting from increased biofuel demand. EPA has used the best available models for this purpose, 

and has incorporated many modifications to its proposed approach based on comments from the 

public, a formal peer review, and developing science. EPA has also quantified the uncertainty associated with significant components of its analyses, including important factors affecting GHG 

emissions associated with international land use change. EPA is confident that its modeling of 

GHG emissions associated with international land use is comprehensive and provides a reasonable and scientifically robust basis for making threshold determinations. Based on this analysis, 

EPA is determining that:

•	 Ethanol produced from corn starch at a new natural gas, biomass, or biogas fired facility

(or expanded capacity from such a facility) using advanced efficient technologies (ones 

that we expect will be most typical of new production facilities) will meet the 20% GHG 

emission reduction threshold compared to the 2005 gasoline baseline. 

•	 Biobutanol from corn starch also meets the 20% threshold.

•	 Biodiesel and renewable diesel from soy oil or waste oils, fats, and greases will meet the

50% GHG threshold for biomass-based diesel compared to the 2005 petroleum diesel 

baseline. 

•	 Biodiesel and renewable diesel produced from algal oils will also comply with the 50%

threshold should they reach commercial production. 

•	 Ethanol from sugarcane complies with the applicable 50% reduction threshold for advanced

biofuels. 

•	 For cellulosic ethanol and cellulosic diesel, the pathways modeled in our analysis (for

feedstock and production technology) would comply with the 60% GHG reduction 

threshold for cellulosic biofuel. 

•	 Determinations for additional fuels and fuel pathways can be found in Section V of the

preamble.

In addition to finalizing threshold compliance determinations for pathways that we specifically 

modeled, as shown above, in some cases our technical judgment indicates that other pathways 

are likely to be similar enough that we can extend these determinations. These include fuels 

that are produced from five categories of feedstocks similar to those already modeled and which 

are expected to have less or no indirect land use change:

1. Crop residues such as corn stover, wheat straw, rice straw, citrus residue 

2. Forest material including eligible forest thinnings and solid residue remaining from forest 

product production

3. Secondary annual crops planted on existing crop land such as winter cover crops

4. Separated food and yard waste including biogenic waste from food processing 

5. Perennial grasses including switchgrass and miscanthus
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Threshold determinations for certain other pathways were not possible at this time because 

sufficient modeling or data is not yet available. In some of these cases, we recognize that while 

a renewable fuel is already being produced from an alternative feedstock and we have the data 

needed for analysis, we did not have sufficient time to complete the necessary lifecycle GHG 

impact assessment for this final rule. EPA anticipates modeling grain sorghum ethanol, woody 

pulp ethanol, and palm oil biodiesel after this final rule and including the determinations in a 

rulemaking within 6 months.

For other fuels, we are establishing a process whereby a biofuel producer or importer can petition 

the Agency to also consider whether a fuel pathway would be eligible for use in complying with 

an EISA standard. EPA will use the data supplied in the petition to evaluate whether the information for the fuel pathway, combined with information developed in this rulemaking for other 

fuel pathways, is sufficient to allow EPA to determine whether the new fuel pathway qualifies. 

EPA will process these petitions as expeditiously as possible, taking into consideration that some 

fuel pathways are closer to the commercial production stage than others.

Our Analysis

In order to calculate the lifecycle GHG emissions of various fuels, EPA utilized models that 

take into account energy and emissions inputs for fuel and feedstock production, distribution, 

and use, as well as economic models that predict changes in agricultural markets. In developing 

this analysis, the Agency employed a collaborative, transparent, and science-based approach. 

Through technical outreach, the peer review process, and the public comment period, EPA 

received and reviewed a significant amount of data, studies, and information on our proposed 

lifecycle analysis approach. We incorporated a number of new, updated, and peer-reviewed data 

sources in our final rulemaking analysis, including better satellite data for tracking land use 

changes and improved assessments of N2O impacts from agriculture. 

We also performed dozens of new modeling runs, uncertainty analyses, and sensitivity analyses 

which are leading to greater confidence in our results. We have updated our analyses in conjunction with, and based on, advice from experts from government, academia, industry, and not for 

profit institutions. 

The new studies, data, and analysis performed for the final rulemaking impacted the lifecycle 

GHG results for biofuels in a number of different ways. In some cases, updates caused the modeled analysis of lifecycle GHG emissions from biofuels to increase, while other updates caused 

the modeled emissions to be reduced. Overall, the revisions since our proposed rule have led to 

a reduction in modeled lifecycle GHG emissions as compared to the values in the proposal. For 

example, for corn ethanol the final rule analysis found less overall indirect land use change (less 

land needed), thereby improving the lifecycle GHG performance of corn ethanol. The main 

reasons for this decrease are:

•	 Based on new studies that show the rate of improvement in crop yields as a function of

price, crop yields are now modeled to increase in response to higher crop prices. When 

higher crop yields are used in the models, less land is needed domestically and globally 

for crops as biofuels expand. 
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•	 New research available since the proposal indicates that distillers grains and solubles

(DGS), a corn ethanol production co-product, is more efficient as an animal feed (meaning less corn is needed for animal feed) than we had assumed in the proposal. Therefore, 

in our analyses for the final rule, domestic corn demand and exports are not impacted as 

much by increased biofuel production as they were in the proposal analysis. 

•	 Improved satellite data allowed us to more finely assess the types of land converted when

international land use changes occur, and this more precise assessment led to a lowering of modeled GHG impacts. Based on previous satellite data, the proposal assumed 

cropland expansion onto grassland would require an amount of pasture to be replaced 

through deforestation. For the final rulemaking analysis we incorporated improved satellite data, as well as improved economic modeling of pasture demand, and found that pasture is also likely to expand onto existing grasslands. This reduced the GHG emissions 

associated with an amount of land use change. 

Next Steps/Future Work

While EPA is using its current lifecycle assessments to inform regulatory determinations in this 

final rule, as required by EISA, we also recognize that as the state of scientific knowledge continues to evolve in this area, the lifecycle GHG assessments for a variety of fuel pathways will 

continue to be enhanced. Therefore, the Agency is committing to further reassess these determinations and lifecycle estimates. As part of this ongoing effort, we will ask for the expert advice 

of the National Academy of Sciences, as well as other experts, and incorporate their advice 

and any updated information we receive into a new assessment of the lifecycle GHG emissions 

performance of the biofuels being evaluated in this final rule. EPA will request that the National 

Academy of Sciences evaluate the approach taken in this rule, the underlying science of lifecycle assessment, and in particular indirect land use change, and make recommendations for 

subsequent lifecycle GHG assessments on this subject. This new assessment could result in new 

determinations of threshold compliance compared to those included in this rule. These would 

apply to future production from plants that are constructed after each subsequent rule incorporating a revised lifecycle assessment methodology. 

Additional detail on the different components of EPA’s lifecycle analysis can be found in the 

preamble and the Regulatory Impact Analysis that accompany the Final Rule. 

For More Information 

For more information on this proposal, please contact EPA’s Office of Transportation and Air 

Quality, Assessment and Standards Division information line at: 

U.S. Environmental Protection Agency 

Office of Transportation and Air Quality 

2000 Traverwood Drive 

Ann Arbor, MI 48105 

Voicemail: (734) 214-4636

E-mail: asdinfo@epa.gov

Or visit: www.epa.gov/otaq/renewablefuels/index.htm