RENEWABLE FUEL 

STANDARD

Program Unlikely to 

Meet Its Targets for 

Reducing 

Greenhouse Gas 

Emissions

Report to the Chairman, Subcommittee 

on Regulatory Affairs and Federal 

Management, Committee on Homeland 

Security and Governmental Affairs, 

U.S. Senate

November 2016

GAO-17-94

United States Government Accountability Office
United States Government Accountability Office

Highlights of GAO-17-94, a report to the

Chairman, Subcommittee on Regulatory 

Affairs and Federal Management, Committee 

on Homeland Security and Governmental 

Affairs, U.S. Senate

November 2016

RENEWABLE FUEL STANDARD

Program Unlikely to Meet Its Targets for Reducing 

Greenhouse Gas Emissions

Why GAO Did This Study

The RFS generally mandates that 

domestic transportation fuels be 

blended with increasing volumes of 

biofuels through 2022, with the goals of 

reducing greenhouse gas emissions 

and expanding the nation’s renewable 

fuels sector while reducing reliance on 

imported oil. Annual targets for the 

volumes of biofuels to be blended are 

set by statute. EPA oversees the 

program and is responsible for

adjusting the statutory targets through 

2022 to reflect expected U.S. industry 

production levels, among other factors,

and for setting biofuel volume targets 

after 2022. Biofuels included in the 

RFS are conventional (primarily cornstarch ethanol) as well as various 

advanced biofuels (including cellulosic 

ethanol and biomass-based diesel). 

Advanced biofuels emit fewer 

greenhouse gases than petroleum and

corn-starch ethanol.

GAO was asked to review challenges

to the RFS and their possible solutions. 

This report provides information on

whether the RFS is expected to meet 

its goals, as well as expert views on 

any federal actions that could improve

the RFS framework, among other 

things. GAO worked with the National 

Academy of Sciences to identify 

experts on issues related to the RFS. 

GAO interviewed these experts and 

analyzed their responses. This report 

also drew on published studies, and a 

companion report, GAO-17-108, that 

examined federal research and 

development in advanced biofuels and 

related issues. EPA generally agreed 

with the report.

What GAO Found

It is unlikely that the goals of the Renewable Fuel Standard (RFS)—reduce 

greenhouse gas emissions and expand the nation’s renewable fuels sector—will 

be met as envisioned because there is limited production of advanced biofuels to 

be blended into domestic transportation fuels and limited potential for expanded

production by 2022. Advanced biofuels achieve greater greenhouse gas 

reductions than conventional (primarily corn-starch ethanol), while the latter

accounts for most of the biofuel blended under the RFS. As a result, the RFS is 

unlikely to achieve the targeted level of greenhouse gas emissions reductions. 

For example, the cellulosic biofuel blended into the transportation fuel supply in 

2015 was less than 5 percent of the statutory target of 3 billion gallons. In part as 

a result of low production, EPA has reduced the RFS targets for advanced 

biofuels through waivers in each of the last 4 years (see figure). According to 

experts GAO interviewed, the shortfall of advanced biofuels is the result of high 

production costs, and the investments in further research and development 

required to make these fuels more cost-competitive with petroleum-based fuels 

even in the longer run are unlikely in the current investment climate.

Volumes of Advanced Biofuels to Be Blended into Domestic Transportation Fuel, as Set by the 

Renewable Fuel Standard Statute and by EPA, 2010 through 2017

Note: As of September 2016, EPA volumes for 2017 are proposed, except for the biomass-based diesel volume for 

2017, which is final.

Experts cited multiple federal actions that they suggested could incrementally

improve the investment climate for advanced biofuels. For example, some 

experts told GAO that maintaining a consistent tax credit for biofuels, rather than 

allowing it to periodically lapse and be reinstated, could reduce uncertainty and 

encourage investment in advanced biofuels.

View GAO-17-94. For more information, 

contact Frank Rusco at (202) 512-3841 or 

ruscof@gao.gov.
Page i GAO-17-94 Renewable Fuel Standard

Letter 1

Background 3

The RFS Is Expected to Fall Short of Its Targets, Because of 

Limited Production of Advanced Biofuels and Reliance on 

Conventional Corn-Starch Ethanol 10

Experts Suggested Multiple Federal Actions That Could 

Incrementally Encourage Investment in Advanced Biofuels and 

Increase Compatibility of Infrastructure with Higher Ethanol 

Blends 14

Experts Suggested Policy Alternatives That Could More Efficiently 

Reduce Greenhouse Gas Emissions 19

Agency Comments and our Evaluation 21

Appendix I Scope and Methodology 22

Appendix II List of Experts’ Names Provided by the National Academy of Sciences 24

Appendix III Comments from the Environmental Protection Agency 25

Appendix IV GAO Contact and Staff Acknowledgments 28

Table

Table 1: List of Experts’ Names Provided by the National 

Academy of Sciences 24

Figures

Figure 1: Statutory Volume Targets under the Renewable Fuel 

Standard, 2006 through 2022 5

Figure 2: Volumes of Advanced Biofuels to Be Blended into 

Domestic Transportation Fuel, as Set by the Renewable 

Fuel Standard Statute and by EPA, 2010 through 2017 6

Figure 3: Volumes of All Biofuels to Be Blended into Domestic 

Transportation Fuel, as Set by the Renewable Fuel 

Standard Statute and by EPA, 2010 through 2017 8

Contents
Page ii GAO-17-94 Renewable Fuel Standard

Abbreviations

DOE Department of Energy

EISA Energy Independence and Security Act of 2007

EMTS EPA Moderated Transaction System

EPA Environmental Protection Agency

LCFS Low carbon fuel standard 

RFS Renewable Fuel Standard

RIN Renewable identification number

USDA U.S. Department of Agriculture

This is a work of the U.S. government and is not subject to copyright protection in the 

United States. The published product may be reproduced and distributed in its entirety 

without further permission from GAO. However, because this work may contain 

copyrighted images or other material, permission from the copyright holder may be 

necessary if you wish to reproduce this material separately.
Page 1 GAO-17-94 Renewable Fuel Standard

441 G St. N.W.

Washington, DC 20548

November 28, 2016

The Honorable James Lankford

Chairman

Subcommittee on Regulatory Affairs and Federal Management

Committee on Homeland Security and Governmental Affairs

United States Senate

Dear Mr. Chairman:

Since 2006, the Renewable Fuel Standard (RFS) has required that 

transportation fuels—typically gasoline and diesel—sold in the United 

States contain annually increasing amounts of renewable fuels, such as 

ethanol and biodiesel, to achieve key environmental and energy goals.1

However, renewable fuels production has not grown to the statutory 

targets. The Environmental Protection Agency (EPA), which is 

responsible for implementing the RFS, defines the goals of the RFS as to 

(1) reduce greenhouse gas emissions and (2) expand the nation’s 

renewable fuel (or biofuel) sector while reducing reliance on imported oil. 

In addition, many experts and industry stakeholders agree that the RFS 

has an implicit purpose of supporting the domestic agricultural economy. 

Each year, by November 30, EPA is required to establish via rulemaking 

the volumes of biofuel that must be blended with transportation fuels 

during the following calendar year (volume requirement).2 The statute 

provides EPA with waiver authority to set volumes below the targets 

specified in the statute under certain circumstances, such as when there 

is “inadequate domestic supply.”3

Our past work has shown that implementation of the RFS faces many 

challenges. In June 2011, we found that problems with transporting, 

selling, and using gasoline blended with more than 10 percent ethanol 

created challenges to meeting the volumes in the statute.4 For example, 

 1

The RFS was established by the Energy Policy Act of 2005, Pub. L. No. 109-58 (2005), 

and expanded in 2007 by the Energy Independence and Security Act, Pub. L. No. 110-

140 (2007). The current statutory requirements are codified at 42 U.S.C. § 7545(o).

2

42 U.S.C. § 7545(o)(3)(B). 

3

42 U.S.C. § 7545(o)(7).

4

GAO, Biofuels: Challenges to the Transportation, Sale, and Use of Intermediate Ethanol 

Blends, GAO-11-513 (Washington, D.C.: June 3, 2011).

Letter
Page 2 GAO-17-94 Renewable Fuel Standard

we found that these higher ethanol blends may require costly 

infrastructure improvements, such as replacing of underground storage 

tanks at filling stations. In March 2014, we found that EPA had been late 

in setting most annual RFS volume requirements for 2009 through 2014, 

adding to investment uncertainty for refiners and other market 

participants.5 We recommended that EPA develop a plan to address 

these delays. Subsequently, EPA set the volume requirement for 2016 on 

time and is on schedule to finalize the proposed volume requirement for 

2017. However, some of the volume requirements that EPA has set and 

proposed have been controversial among RFS stakeholders. For 

example, agricultural groups have stated in public comments that EPA 

should further increase volumes of conventional corn-starch ethanol—the 

biofuel predominantly used in the United States—to encourage 

investment in the infrastructure needed to accommodate fuel blends with 

a higher percentage of ethanol. In contrast, petroleum industry 

representatives have stated that increasing these volume requirements is 

unrealistic because there is insufficient demand for higher ethanol blends, 

and small engine manufacturers have stated that EPA is increasing 

ethanol volumes to levels dangerous to boat engines and small engines, 

such as those in lawn mowers.

You asked us to provide information about the RFS, the challenges to its 

implementation, and possible solutions or policy alternatives. This report 

provides information on (1) whether the RFS is expected to meet its 

goals, (2) expert views on any federal actions that could improve the RFS 

framework, and (3) policy alternatives experts suggested to better meet 

the goals of the RFS in the future.

To address our objectives, we contracted with the National Academy of 

Sciences for a list of experts on issues related to the RFS. The National 

Academy of Sciences identified 24 experts with whom we conducted 

semistructured interviews. We analyzed the content of the experts’

responses to our questions, coding their responses into categories 

pertinent to our objectives.6 In addition, we reviewed the public comments 

from stakeholders on rules proposed by EPA in 2015 and 2016, relevant 

 5

GAO, Petroleum Refining: Industry’s Outlook Depends on Market Changes and Key 

Environmental Regulations, GAO-14-249 (Washington, D.C.: Mar. 14, 2014).

6

For reporting purposes, we categorized expert responses as follows: “nearly all” experts 

represents 21 to 23 experts; “most” experts represents 16 to 20 experts; “many” experts 

represents 11 to 15 experts; “several” experts represents 6 to 10 experts; and “some”

experts represents 2 to 5 experts.
Page 3 GAO-17-94 Renewable Fuel Standard

legislation, and agency documents pertaining to annual volume 

requirements (e.g., EPA’s response to public comments) and conducted a 

literature search of academic articles analyzing the RFS and other policy 

approaches. We also interviewed Congressional Research Service 

officials who have conducted extensive work on the RFS.7 In addition, we 

interviewed officials at EPA, the Department of Energy (DOE), and the 

Department of Agriculture (USDA). Finally, this report drew from a 

companion report, GAO-17-108, that examined federal research and 

development in advanced biofuels and related issues.8

We conducted this performance audit from June 2015 to November 2016 

in accordance with generally accepted government auditing standards. 

Those standards require that we plan and perform the audit to obtain 

sufficient, appropriate evidence to provide a reasonable basis for our 

findings and conclusions based on our audit objectives. We believe that 

the evidence obtained provides a reasonable basis for our findings and 

conclusions based on our audit objectives.

In response to concerns about the nation’s dependence on imported oil, 

Congress enacted the RFS program as part of the Energy Policy Act of 

2005. This initial RFS required that a minimum of 4 billion gallons of 

biofuels be used in 2006, rising to 7.5 billion gallons by 2012. Two years 

later, the Energy Independence and Security Act of 2007 (EISA) 

expanded the biofuel target volumes and extended the ramp-up through 

2022 establishing overall target volumes for biofuels that increase from 9 

billion gallons in 2008 to 36 billion gallons in 2022. The EISA volumes can 

 7

See, for example, Congressional Research Service, The Renewable Fuel Standard 

(RFS): Waiver Authority and Modification of Volumes, R44045 (Washington, D.C.: Feb. 

10, 2016); The Renewable Fuel Standard (RFS): In Brief, R43325 (Washington, D.C.: 

Feb. 4, 2016); Analysis of Renewable Identification Numbers (RINs) in the Renewable 

Fuel Standard (RFS), R42824 (Washington, D.C.: July 22, 2013); The Renewable Fuel 

Standard (RFS): Compliance and Penalties (Washington, D.C.: Feb. 5, 2015); and 

Renewable Fuel Standard (RFS): Overview and Issues, R40155 (Washington, D.C.: Nov. 

22, 2013).

8

GAO, Renewable Fuel Standard: Low Expected Production Volumes Make It Unlikely 

That Advanced Biofuels Can Meet Increasing Targets, GAO-17-108, (Washington, D.C.: 

Nov. 23 2016). 

Background
Page 4 GAO-17-94 Renewable Fuel Standard

be thought of in terms of two broad categories: conventional and 

advanced biofuels:9

Conventional biofuel: Biofuels from new facilities must achieve at least 

a 20-percent reduction in greenhouse gas emissions, relative to 2005 

baseline petroleum-based fuels. The dominant biofuel produced to date is 

conventional corn-starch ethanol, although recently some conventional

biodiesel has entered the fuel supply.10

Advanced biofuel: Biofuels, other than ethanol derived from corn starch 

must achieve at least a 50-percent reduction in life-cycle greenhouse gas 

emissions, as compared with 2005 baseline petroleum-based fuels. This 

is a catch-all category that may include a number of fuels, including fuels 

made from any qualified renewable feedstock that achieves at least a 50-

percent reduction in lifecycle greenhouse gas emissions, such as ethanol 

derived from cellulose, sugar, or waste material. This category also 

includes the following:

• Biomass-based diesel: Advanced biomass-based diesel must have 

life-cycle greenhouse gas emissions at least 50 percent lower than 

traditional petroleum-based diesel fuels.

• Cellulosic biofuel: Advanced biofuel derived from any cellulose, 

hemicellulose, or lignin that is derived from renewable biomass must 

have life-cycle greenhouse gas emissions at least 60 percent lower 

than traditional petroleum-based fuels.11 This category of fuel may 

include cellulosic ethanol, renewable gasoline, cellulosic diesel, and 

renewable natural gas from landfills that can be used to generate 

 9

The statutory categories are renewable fuel, advanced biofuel, cellulosic biofuel, and 

biomass-based diesel. Conventional biofuels are defined as renewable fuels that are 

ethanol derived from corn starch. A fuel may qualify for one or more categories for 

purposes of meeting the volume requirements. For example, cellulosic biofuel may be 

used to meet the cellulosic biofuel volume requirement, the advanced biofuel requirement, 

and the renewable fuel requirement. However, conventional biofuels such as corn-based 

ethanol count toward meeting only the renewable fuel volume requirement.

10Corn-starch ethanol plants that were in operation or under construction before 

December 19, 2007, are not subject to the requirement to reduce greenhouse gas 

emissions by at least 20 percent.

11Plant biomass is made up primarily of cellulose, hemicellulose, and lignin. Cellulose and 

hemicellulose are made up of potentially fermentable sugars. Lignin provides the 

structural integrity of plants by enclosing the tightly linked cellulose and hemicellulose 

molecules, which makes these molecules harder to reach.
Page 5 GAO-17-94 Renewable Fuel Standard

electricity for electric vehicles or used in vehicles designed to run on 

liquefied or compressed natural gas.

The RFS required the annual use of 4 billion gallons of overall biofuels in 

2006, rising to 36 billion gallons in 2022, with at least 21 billion gallons 

from advanced biofuels, effectively capping the volume of biofuels 

(primarily conventional, or corn-starch, ethanol) that may be counted 

toward the overall 2022 target of 15 billion gallons.

Figure 1: Statutory Volume Targets under the Renewable Fuel Standard, 2006 through 2022

Note: Although the figure lists “conventional biofuels” as a separate category, the statute includes 

conventional biofuels as part of the broader category of “renewable fuel;” thus, other categories of 

fuels could be used to meet the requirement for this category. The figure illustrates how conventional 

fuels may be used only up to a point to meet statutory volume targets and that, by 2015, that point 

would be reached; thus, all additional gallons of renewable fuels would have to come from advanced 

biofuels.

EPA administers the RFS in consultation with DOE and USDA. EPA’s 

responsibilities for implementing the RFS include setting annual volume 

requirements and, in doing so, using its waiver authority to reduce 

statutory volume targets, if warranted. As figure 1 shows, the structure of 
Page 6 GAO-17-94 Renewable Fuel Standard

the volume targets allowed for blending of conventional corn-starch 

ethanol in the early years covered by the statute while providing lead time 

for the development and commercialization of advanced, and especially 

cellulosic, biofuels. However, these fuels have not been produced in 

sufficient quantities to meet statutory targets through 2016. As a result, 

since 2010, EPA has used its waiver authority to deviate from the 

statutory target volumes and has reduced the volume requirement for 

cellulosic biofuel every year, citing inadequate domestic supply, among 

other things (see fig.2).12

Figure 2: Volumes of Advanced Biofuels to Be Blended into Domestic Transportation Fuel, as Set by the Renewable Fuel 

Standard Statute and by EPA, 2010 through 2017

Note: As of September 2016, EPA volumes for 2017 are proposed, except for the biomass-based 

diesel volume for 2017, which is final.

 12The law provides that for any calendar year for which the projected volume of cellulosic 

biofuel production is less than the statutory volume, the Administrator of EPA must reduce 

the applicable volume of cellulosic biofuel to the projected volume available during that 

calendar year. 42 U.S.C. § 7545(o)(7)(D)(i).
Page 7 GAO-17-94 Renewable Fuel Standard

In December 2015—when EPA finalized the volume requirements for 

2014, 2015, and 2016—the agency reduced the total renewable fuel 

requirement for those years.13 Effectively, this meant that EPA reduced 

the amount of conventional biofuels required under the program relative 

to statutory targets for those years. Similarly, in the volume requirement 

proposed in May 2016, EPA also proposed reducing the total renewable 

fuel requirement for 2017 compared with the target volumes in the 

statute: from 24 to 18.8 billion gallons (see fig.3).14 In both cases, EPA 

cited constraints in the fuel market’s ability to accommodate increasing 

volumes of ethanol. EPA’s use of this waiver authority has been 

controversial among some RFS stakeholders, and EPA’s 2015 

requirement currently faces legal challenges from multiple parties.

 13In December 2015, when EPA finalized its volume requirement for 2016, it retroactively 

established volumes for 2014 and 2015. Renewable Fuel Standard Program: Standards 

for 2014, 2015, and 2016 and Biomass-Based Diesel Volume for 2017; Final Rule, 80 

Fed. Reg. 77420 (2015).

14Renewable Fuel Standard Program: Standards for 2017 and Biomass-Based Diesel 

Volume for 2018; Proposed Rule, 81 Fed. Reg. 34778 (2016).
Page 8 GAO-17-94 Renewable Fuel Standard

Figure 3: Volumes of All Biofuels to Be Blended into Domestic Transportation Fuel, as Set by the Renewable Fuel Standard 

Statute and by EPA, 2010 through 2017

Note: As of September 2016, EPA volumes for 2017 are proposed, except for the biomass-based 

diesel volume for 2017, which is final. Although the figure lists “conventional biofuels” as a separate 

category, the statute includes conventional biofuels as part of the broader category of “renewable 

fuel”; thus, other categories of fuels could be used to meet the requirement for this category.

EPA’s responsibilities for the RFS also include determining companies’

compliance with the RFS. EPA regulates compliance with the RFS using 

a credit system. Companies in the United States that refine or import 

transportation fuel must submit credits—called renewable identification 

numbers (RIN)—to EPA. Companies with such an obligation are known 

as “obligated parties.” The number of RINs that an obligated party must 

submit to EPA is proportional to the volume of gasoline and diesel fuel 

that the obligated party produces or imports and depends on the total 

volume requirement EPA sets for the year in question. In accordance with 

EPA guidelines, a biofuel producer or importer assigns a unique RIN to a 

gallon of biofuel at the point of production or importation. When biofuels 

change ownership (e.g., are sold by a producer to a blender), the RINs 

generally transfer with the fuels. When a gallon of biofuel is blended or 
Page 9 GAO-17-94 Renewable Fuel Standard

supplied for retail sale, the RIN is separated from the fuel and may be 

used for compliance or traded, sold, or held for use in the following year. 

Since biofuels supply and demand can vary over time and across regions, 

a market has developed for trading RINs. If a supplier has already met its 

required share and has supplied surplus biofuels for a particular biofuel 

category, it can sell the extra RINs to another entity or it can hold onto the 

RINs for future use. An obligated party that faces a RIN deficit can 

purchase RINs to meet its obligation.15

Since the establishment of the RFS, conventional corn-starch ethanol is 

the biofuel that has most often been blended with gasoline. After 

production, ethanol is blended into the gasoline either by the wholesale 

distributor or at the retail pump, with both requiring specialized tanks and 

pumping equipment. Retailers sell specific blends of gasoline and 

ethanol: E10 (up to 10 percent ethanol); E85 (51 to 85 percent ethanol); 

and, less typically, E15 (15 percent ethanol). E10 is the most widely used 

blend, representing the overwhelming majority of gasoline sales in the 

United States. The E85 blend is specifically used by flex fuel vehicles.

Currently, there are relatively few of these automobiles in the United 

States, and E85 stations are located primarily in the Midwest.16 The sale 

of E15 blend is even less common than that of E85. For both E85 and 

E15, developing retail pump infrastructure has been a focus of USDA’s 

Biofuel Infrastructure Partnership which, beginning in 2015, has made 

$100 million available in matching grants in 21 states to install nearly 

5,000 new retail pumps.

In the years since the RFS was established, U.S. oil imports have 

decreased. Several factors contributed to the decrease in reliance on 

imported oil, including the use of E10 brought about by the RFS. 

However, other factors contributed more significantly to the decrease. 

According to an April 2015 DOE report, at the same time that U.S. oil 

production was growing, U.S. oil consumption, and particularly 

consumption of gasoline, was falling. A number of factors led to the 

 15RINs may be used for RFS compliance in the year they were generated or the following 

calendar year. No more than 20 percent of the current-year obligation may be met with the 

previous year’s RINs. The EPA Moderated Transaction System (EMTS) is used to register 

RIN transactions.

16According to the U.S. Energy Information Administration, in the United States in 2016, 

there were approximately 19.61 million flex fuel vehicles—designed to use any fuel blend 

up to E85—compared with 242.55 million total light-duty vehicles.
Page 10 GAO-17-94 Renewable Fuel Standard

decrease in consumption, including historic fuel economy standards for 

light and heavy vehicles in recent years.17

It is unlikely that the goals of the RFS will be met as envisioned because 

there is limited production of advanced biofuels to be blended into 

domestic transportation fuels and limited potential for expanded 

production by 2022. In the absence of advanced biofuels, most of the 

biofuel blended under the RFS to date has been conventional corn-starch 

ethanol, which achieves smaller greenhouse gas emission reductions 

compared with advanced biofuels. In addition, further reliance on ethanol 

to meet expanding RFS requirements is limited by incompatibility of 

ethanol blends above E10 with existing vehicle fleet and fueling 

infrastructure.

It is unlikely that the goals of the RFS—to reduce greenhouse gas 

emissions and expand the nation’s renewable fuels sector—will be met as 

envisioned because there is limited production of advanced biofuels to be 

blended into domestic transportation fuels and limited potential for 

expanded production by 2022. As we report in GAO-17-108, advanced 

biofuels are technologically well understood, but current production is far 

below the volume needed to meet the statutory targets for these fuels.18

For example, the cellulosic biofuel blended into transportation fuel in 2015 

was less than 5 percent of the statutory target of 3 billion gallons. Given 

current production levels, most experts we interviewed told us that 

advanced biofuel production cannot achieve the statutory targets of 21 

billion gallons by 2022.

The shortfall of advanced biofuels is the result of high production costs, 

despite years of federal and private research and development efforts. 

The RFS was designed to bring about reductions in greenhouse gas 

emissions by blending targeted volumes of advanced and, in particular, 

cellulosic, biofuels, because those fuels achieve greater greenhouse gas 

reductions than conventional corn-starch ethanol and petroleum-based 

fuel. However, because advanced biofuel production is not meeting the 

 17Department of Energy, Quadrennial Energy Review: Energy Transmission, Storage, and 

Distribution Infrastructure, (Washington, D.C.: Apr. 2015).

18GAO-17-108. 

The RFS Is Expected 

to Fall Short of Its 

Targets, Because of 

Limited Production of 

Advanced Biofuels 

and Reliance on 

Conventional CornStarch Ethanol

Limited Production of 

Advanced Biofuels Makes 

the RFS Unlikely to Meet 

Its Goals
Page 11 GAO-17-94 Renewable Fuel Standard

RFS’s targets, the RFS is limited in its ability to meet its greenhouse gas 

reduction goals as envisioned. According to several experts we 

interviewed, the investments and development required to make these 

fuels more cost-effective, even in the longer run, are unlikely in the 

current investment climate, in part because of the magnitude of 

investment and the expected long time frames required to make 

advanced biofuels cost-competitive with petroleum-based fuels.

In the absence of advanced biofuels, most of the biofuel blended under 

the RFS to date has been conventional corn-starch ethanol, which 

achieves smaller greenhouse gas emission reductions than advanced 

biofuels. As stated above, the use of corn-starch ethanol has been 

effectively capped at 15 billion gallons. As a result, further expansion of 

biofuels use will require increasing cellulosic biofuels and, according to 

report’s companion report (GAO-17-108), the most likely cellulosic biofuel 

to be commercially produced in the near- to midterm will be cellulosic 

ethanol. However, reliance on adding more ethanol to the transportation 

fuel market to meet expanding RFS requirements is limited by the 

incompatibility of ethanol blends above E10 with the existing vehicle fleet 

and fueling infrastructure. Many experts and stakeholders refer to this 

infrastructure limitation as the “blend wall.” If ethanol continues to be the 

primary biofuel produced to meet the RFS, these infrastructure limitations 

will have to be addressed.

Specifically with regard to the existing vehicle fleet, some experts told us 

that for most vehicles sold in the United States before 2015, the owner’s 

manuals and warranties indicate that the vehicles should not use ethanol 

blends above 10 percent because of concerns about engine performance. 

Since 2011, EPA has issued waivers to the Clean Air Act allowing 

automobiles and light-duty trucks from model year 2001 and after to run 

on E15. However, many auto manufacturers contest this waiver, stating 

that automobile owners should follow their owner’s manuals. The 

possibility that using higher blends of ethanol than E10 will cause vehicle 

warrantees to be void may be reducing demand for these higher blends of 

ethanol. Flex fuel vehicles, which can run on ethanol blends up to E85, 

have entered the vehicle fleet but, as of 2016, were less than 10 percent 

of the total vehicle fleet, which may also limit the potential demand for 

The RFS Has Relied on 

Corn-Starch Ethanol, 

Which in Higher Blends Is 

Incompatible with Existing 

Infrastructure and Offers 

Comparatively Small 

Greenhouse Gas 

Reductions
Page 12 GAO-17-94 Renewable Fuel Standard

higher blends of ethanol.19 Further, several experts told us there is little 

demand from the public for E85 because the fuel offers lower gas mileage 

than E10 or E15 and prices of E85 do not reflect the need to refuel more 

frequently. Some experts told us that the demand for E85 has not been 

truly tested because the public (including owners of flex fuel vehicles) is 

largely undereducated about E85.

With regard to the fueling infrastructure, some experts stated that ethanol 

blends higher than E10 are largely incompatible with existing distribution 

and retail fueling tanks and pumps in the United States and that there are 

few incentives for fuel distributors and retailers to make the changes that 

would be needed to accommodate higher blends. Retail sale of these 

higher blends faces three key challenges:

• Compatibility. Ethanol blends higher than E10 may degrade or 

damage some materials used in existing underground storage tank 

systems and dispensing equipment such as pumps, potentially 

causing leaks.

• Cost. Because of concerns over compatibility, new storage and 

dispensing equipment may be needed to sell intermediate blends at 

retail outlets. The cost of installing a single-tank underground storage 

system compatible with intermediate blends is more than $100,000. In 

addition, the cost of installing a single compatible fuel dispenser is 

over $20,000.

• Liability. Since EPA has authorized E15 for use in model year 2001 

and newer automobiles—but not for pre-2001 vehicles or nonroad 

engines—many fuel retailers are concerned about potential liability 

issues if consumers mistakenly use e15 in their older automobiles or 

nonroad engines.

Several experts raised concerns about the extent to which the RFS is 

achieving its targeted greenhouse gas emissions reductions, given that 

most biofuel blended under the RFS is corn-starch ethanol. More 

specifically, some experts were critical of the life-cycle analysis EPA used 

to determine the greenhouse gas emissions reductions for corn-starch 

ethanol. This criticism focuses on whether the model accurately accounts 

for all greenhouse gas emissions in the corn-starch ethanol production 

process. Some experts said that EPA’s life-cycle analysis is flawed 

 19The U.S. Energy Information Administration reports that in 2016 there were 

approximately 19.6 million flexible fuel vehicles on the road designed to use any fuel blend 

up to E85. However, most of these vehicles are not using E85.
Page 13 GAO-17-94 Renewable Fuel Standard

because it does not sufficiently include indirect land use change.20

Further, as previously stated in this report, corn-starch ethanol plants that 

were in operation or under construction before December 19, 2007, were 

not subject to the requirement to reduce greenhouse gas emissions by at 

least 20 percent. According to an August 2016 EPA Inspector General 

report, grandfathered production that is not subject to any greenhouse 

gas reduction requirements was estimated to be at least 15 billion 

gallons, or over 80 percent of today’s RFS blending volume.21 Moreover, 

some experts noted that under the RFS, because these facilities are 

grandfathered, they have no incentive to lower their greenhouse gas 

emissions. Some experts told us that the RFS creates a perverse 

incentive to import Brazilian sugarcane ethanol. Specifically, because 

sugarcane ethanol qualifies as an advanced biofuel, it is more profitable 

to import this fuel than to domestically produce advanced biofuels. 

According to these experts, the import of sugarcane ethanol, which 

occurs to meet RFS requirements, causes significant greenhouse gas 

emissions as a result of fuel burned during shipping.

 20Indirect land use change refers to the idea that diversion of an acre of traditional field 

cropland to grow a biofuels feedstock crop might result in the displaced traditional crop 

being planted on virgin soil. Such a transfer, if included in calculating the life-cycle 

greenhouse gas emissions of a particular biofuel, could result in an estimated net increase 

in emissions.

21Environmental Protection Agency, Office of Inspector General, EPA Has Not Met 

Certain Statutory Requirements to Identify Environmental Impacts of Renewable Fuel 

Standard, 16-P-0275 (Washington, D.C.: Aug. 18, 2016).
Page 14 GAO-17-94 Renewable Fuel Standard

While advanced biofuels are not likely to be produced in sufficient 

quantities to meet the statutory targets, experts identified actions that they 

suggested could incrementally improve investment in advanced biofuels 

and may lead to greater volumes of these fuels being produced and used 

in the longer term. In addition, experts identified actions to increase 

compatibility of infrastructure with higher ethanol blends.

Experts identified actions that they suggested could incrementally 

improve the investment climate for advanced biofuels and possibly 

encourage the large investments and rapid development required to 

make these fuels more cost-effective.

Addressing uncertainty about the future of the RFS: Many experts 

told us that uncertainty about the future of the RFS is limiting investment 

in advanced biofuels. In particular, some experts stated that the possibility 

of a repeal of the RFS has caused potential investors to question whether 

the RFS will continue to exist until 2022 and beyond. According to these 

experts, however, in the current political climate little can be done to 

address the threat of a repeal of the RFS. EPA may be able to improve 

the investment climate for advanced biofuels by clarifying its plans for 

managing the program in upcoming years. Specifically, statutory volume 

targets have been set through 2022. After that, EPA will be responsible 

for setting these volumes. One expert said that if EPA provided more 

insight into its plans for setting post-2022 volume targets, it could reduce 

some of this investment uncertainty. Further, the annual requirement that 

EPA finalized in 2015 triggered what is commonly referred to as the “reset 

provision” of the RFS for the advanced biofuel and cellulosic biofuel 

categories. The reset provision requires EPA to modify the statutory 

volume targets for future years if certain conditions are met (see sidebar). 

Although the statute provides factors for EPA to consider when modifying 

these volumes, EPA has not specified how it will approach setting 

Experts Suggested 

Multiple Federal 

Actions That Could 

Incrementally 

Encourage 

Investment in 

Advanced Biofuels 

and Increase 

Compatibility of 

Infrastructure with 

Higher Ethanol 

Blends

Experts Identified Actions 

That Could Incrementally 

Encourage Investment in 

Advanced Biofuels

The reset provision provides that, if EPA 

waives any of the biofuel category 

requirements

• by at least 20 percent for 2 consecutive 

years or 

• by at least 50 percent for a single year 

EPA shall modify the statutory volume targets 

for all subsequent years. EPA—in 

coordination with the DOE and USDA—must 

determine the applicable volumes based on a 

review of program implementation thus far 

and analysis of certain factors (e.g., the 

impact of the production and use of biofuels 

on the environment).

Source: 42 U.S.C. § 7545(o)(7)(F). | GAO17-94
Page 15 GAO-17-94 Renewable Fuel Standard

volumes under this reset provision. As a result, several experts thought 

that uncertainty about the volumes of advanced and cellulosic biofuels 

affected by the reset may be limiting investments in these fuels. Some 

experts thought that EPA should clarify how it will implement the reset to 

reduce negative impacts on investments in advanced biofuels. EPA 

officials told us that recent annual volume requirements make EPA’s 

intent clear in the near term.

Providing more consistent subsidies to advanced biofuel producers.

Some experts stated that the Second Generation Biofuel Producer Tax 

Credit—an incentive to accelerate commercialization of fuels in the 

advanced and cellulosic biofuels categories—has expired and been 

reinstated (sometimes retroactively) about every 2 years, contributing to 

uncertainty among cellulosic fuel producers and investors. These experts 

told us that investment in cellulosic biofuels could be encouraged, in part, 

by maintaining the Second Generation Biofuel Producer Tax Credit 

consistently, rather than allowing it to periodically lapse and be reinstated. 

Specifically, one expert suggested three major changes to the advanced 

biofuel tax credits:

• Extending the tax credit long term (e.g., 10 years) to provide investors 

sufficient investment return certainty for the large investment of 

building a biofuel plant until a cumulative level of second generation 

biofuel has been produced and costs have fallen.

• Making the producer tax credit refundable to guarantee that biofuel 

producers receive the subsidy in the early years when they are 

carrying losses.22

• Coupling the producer tax credit with an investment tax credit to 

decrease capital costs and improve the financial incentives for 

building cellulosic biofuel plants.

Expanding the types of fuel that qualify for the RFS. The current RFS 

framework specifies that qualifying biofuels must be derived from 

biomass-based feedstocks. According to some experts, this excludes 

some types of low carbon fuels from qualifying under the RFS. One 

example provided by experts is a process that uses microbes that capture 

carbon from industrial sources—such as the waste gas emitted from steel 

production—to produce a biofuel with lower greenhouse gas emissions 

 22According to this expert, currently the Second Generation Biofuel Producer Tax Credit is 

not refundable or reimbursable, so it does not provide value in years when the producer 

has zero or negative tax liability.
Page 16 GAO-17-94 Renewable Fuel Standard

than petroleum-based fuels. However, because this fuel is not derived 

from renewable biomass, it does not qualify for any RFS category. 

According to these experts, expanding the RFS to include fuel types such 

as this would better incentivize investment in innovative technologies.23

Reducing RIN fraud and price volatility. Some experts said that a lack 

of transparency in the RIN trading market has led to an increased risk of 

fraud and increased volatility of RIN prices. This has caused uncertainty 

among potential investors.

• RIN fraud. From the beginning of the RFS program, there have been 

concerns surrounding RIN generation and the RIN market. Because 

RINs are essentially numbers in a computerized account, there have 

been errors and opportunities for fraud, such as double counting RINs 

or generating RINs for biofuels that do not exist.24 To address 

concerns over these issues, EPA established an in-house trading 

system called the EPA Moderated Transaction System (EMTS). 

However, EPA has maintained that verifying the authenticity of RINs 

is the duty of obligated parties. Under this “buyer beware” system, 

those purchasing or receiving RINs must verify the RINs’ validity on 

their own, and they are responsible for any fraudulent RINs they sell 

or submit to EPA for compliance. However, fraud cases in the last few 

years have raised questions about whether this “buyer beware”

system is sufficient to deter fraud. Furthermore, obligated parties that 

inadvertently purchase fraudulent RINs lose the money spent to 

purchase them, must purchase additional RINs to meet their 

obligations, and face additional costs. This has a disproportionate 

effect on small refiners: whereas large obligated parties—in particular, 

vertically integrated refiners that typically own blending operations—

can generate RINs by blending fuel, small refiners do not blend fuel 

and must purchase their RINs on the market to meet their obligations 

and are therefore more likely to be adversely affected by fraudulent 

RINs.

 23In October 2016, EPA proposed several measures that it says will boost production and 

use of biofuels under the RFS. In addition to approving some new advanced biofuel 

pathways that were under review, EPA proposed an updated regulatory structure that 

would allow biofuel producers to partially process renewable feedstocks at one facility and 

further process them into biofuels at another facility under an existing fuel pathway. EPA 

says this would improve production efficiency, particularly for advanced and cellulosic 

biofuels.

24Congressional Research Service, Analysis of Renewable Identification Numbers (RINs) 

in the Renewable Fuel Standard (RFS), R42824 (Washington, D.C.: July 22, 2013).
Page 17 GAO-17-94 Renewable Fuel Standard

• RIN price volatility. Further, according to some experts, price volatility 

in RIN markets adversely affects small refiners in particular and leads 

to uncertainty among investors. While most RINs are bought and sold 

through private contracts registered with the EMTS, there are also 

spot markets for RINs. Some experts told us that price volatility may 

be due, in part, to nonobligated parties speculating in these spot 

markets. According to one expert, the current system leaves small 

refiners disproportionately exposed to RIN price fluctuations because 

they must purchase their RINs on the market, as previously 

discussed. Such price fluctuations introduce uncertainty for small 

refiners about the costs of compliance with the RFS.

These concerns about RIN fraud and price volatility have led to 

uncertainty among potential investors. Some experts told us that EPA 

should make RIN market trading more open and transparent like other 

commodity markets, which could reduce the potential for fraudulent RIN 

activities and reduce RIN price volatility. EPA officials told us that EPA 

has recently begun to publish aggregated data on RIN transactions and 

biofuel volume production on its website in an effort to make the RIN 

market more transparent. However, it is too early to know how effective 

this will be in addressing fraud and price volatility.

Several experts suggested that expanding grants to encourage 

infrastructure improvements, such as USDA’s Biofuel Infrastructure 

Partnership, could increase both the availability and competitiveness of 

higher blends at retail stations nationwide. Currently through this 

partnership, USDA is investing $100 million to install nearly 5,000 pumps 

offering high ethanol blends in 21 states. Some experts also said that 

blender pumps are not being installed with the density required to test 

demand. One expert suggested that, instead of installing blender pumps 

at all the stations of a certain brand in a region, blender pumps should be 

installed at all the stations at a specific road intersection. That way, these 

stations would be forced to compete with each other, which this expert 

told us would result in more competitive prices at the pump and increased 

incentives to make improvements to fueling infrastructure. Further, one 

expert suggested that dealers educate consumers about flex fuel vehicle

features when the vehicles are delivered, as dealers previously did when 

on-board diagnostic, check engine light, and Bluetooth synchronizing 

features were introduced. Under these conditions, demand for higher 

ethanol blends—and E85, in particular—could be better tested. In 

response to these concerns and suggestions, a USDA official told us that, 

while it is not mandatory that installations meet a required geographic

Experts Identified Actions 

to Increase Compatibility 

of Infrastructure with 

Higher Ethanol Blends
Page 18 GAO-17-94 Renewable Fuel Standard

density, many of the blender pumps could be installed on highway 

corridors, which could encourage competition. This official also told us 

that, in addition to expanding infrastructure for higher ethanol blends, the 

Biofuel Infrastructure Partnership will be able to provide data associated 

with testing demand for E85, including pricing, consumer education, and 

next steps for the program. In addition, in October 2016, EPA proposed 

an update to fuel regulations to allow expanded availability of high ethanol 

fuel blends for use in flex fuel vehicles. EPA is proposing revisions to its 

gasoline regulations to make it clear that E16 through E83 fuel blends are 

not gasoline, and hence not fully subject to gasoline quality standards. 

EPA believes these revisions will increase demand for higher ethanol 

blends.

Some experts said that blenders should be the obligated parties, instead 

of importers and refiners, because that would lead to more rapid 

investments in infrastructure for higher ethanol blends. According to some 

experts, when EPA designed the RFS, it placed the obligation for 

compliance on the relatively small number of refiners and importers rather 

than on the relatively large number of downstream blenders in order to 

minimize the number of obligated parties to be regulated and make the 

program easier to administer. However, these experts told us that 

obligating refiners and importers has not worked to incentivize investors 

to expand infrastructure for higher ethanol blends. Specifically, increasing 

consumer demand for biofuels—and the corresponding incentives to 

invest in biofuel infrastructure—requires the value of the RIN be “passed 

through” to consumers. More specifically, because the RIN that 

accompanies the gallon of biofuel has value for demonstrating 

compliance with the RFS or when sold in the market, it can be used to 

offset the higher cost of the biofuel and make it more competitive with 

petroleum-based fuels. By making biofuels more competitive, retailers are 

incentivized to build the infrastructure required to sell more of these fuels 

(i.e., higher ethanol blends). According to some experts and industry 

stakeholders, this pass-through has not been occurring as envisioned 

with refiners and importers as the obligated parties. One expert stated 

that, because blenders are either retailers or sell to retailers, blenders 

would be better situated to pass RIN savings along to consumers. This in 

turn might encourage demand for higher ethanol blends and incentivize 

infrastructure expansion. EPA officials told us they have received several 

petitions requesting that they consider changing the point of obligation 

and are evaluating those petitions.
Page 19 GAO-17-94 Renewable Fuel Standard

Several experts stated that the RFS is not the most efficient way to 

achieve the program’s goal of reducing greenhouse gas emissions, and 

they suggested policy alternatives—in particular, a carbon tax and a low 

carbon fuel standard (LCFS). Some experts stated that the design of the 

RFS may undermine its ability to achieve the greatest greenhouse gas 

emissions reductions. Specifically, some experts said that the RFS does 

not incentivize the production of advanced biofuels, which achieve the 

greatest greenhouse gas emission reductions. For example, a cellulosic 

fuel that reduces greenhouse gas emissions by 80 percent receives no 

more credit under the RFS than one that reduces greenhouse gas 

emissions by 60 percent, the baseline for the cellulosic category. As a 

result, fuels that may be slightly more costly to produce but achieve far 

greater greenhouse gas reductions may not be developed and brought to 

the market. Further, one expert stated that the RFS design creates a 

market rebound effect. That is, increasing the supply of biofuels tends to 

lower energy prices, which encourages additional fuel consumption that 

may actually result in increased greenhouse gas emissions.

Several experts suggested that a carbon tax or an LCFS would be more 

efficient at reducing greenhouse gas emissions. Specifically, some 

experts said that, whereas the RFS creates disincentives for the 

production of cellulosic fuels that achieve the greatest greenhouse gas 

emission reductions, a carbon tax or LCFS would incentivize the 

technologies that achieve the greatest reductions in greenhouse gas 

emissions at the lowest cost. According to one expert, a carbon tax would 

eliminate the need for annual volume requirements and the 

accompanying program management and oversight. Under a carbon tax, 

each fossil fuel would be taxed in proportion to the amount of greenhouse 

gas (carbon dioxide) released in its combustion. In addition, one expert 

stated that a carbon tax is preferable to the RFS because it allows market 

effects to increase the price of emission-causing activities, which 

decreases demand for those activities. As a result, it could sustain 

consumers’ interest in fuel-saving vehicles and would result in a wide 

range of fuel-saving responses from all consumers (rather than just those 

purchasing a new vehicle). However, some experts also noted that a 

carbon tax would force further electrification for light-duty transportation 

because the electric power sector is the cheapest sector from which to 

obtain greenhouse gas reductions. According to one expert, this 

electrification of the light-duty fleet might further limit research and 

development of biofuels, in effect undermining the RFS goal to expand 

that sector.

Experts Suggested 

Policy Alternatives 

That Could More 

Efficiently Reduce 

Greenhouse Gas 

Emissions
Page 20 GAO-17-94 Renewable Fuel Standard

In light of this, several experts said that an LCFS would be more flexible 

and efficient than the RFS at developing biofuels that achieve the 

greatest greenhouse gas reductions. 25 Specifically, an LCFS compares 

cost with greenhouse gas intensity (by accounting for carbon on a cost 

per unit of carbon intensity), thereby supporting incremental carbon 

reductions. An LCFS can be implemented in one of two ways. The first 

involves switching to direct fuel substitutes (e.g., drop-in fuels) or blending 

biofuels with lower greenhouse gas emissions directly into gasoline and 

diesel fuel. The second involves switching from petroleum-based fuels to 

other alternatives, such as natural gas, hydrogen, or electricity, because a 

low carbon fuel standard would allow a wider array of fuel pathways than 

the RFS. Under the first scenario, an LCFS would promote biofuel usage, 

rather than incentivizing electrification of the light-duty vehicle fleet. As a 

result, according to some experts, an LCFS is preferable to a carbon tax 

because it more efficiently reduces greenhouse gas emissions and 

promotes the expansion of the biofuel sector. However, other experts we 

spoke with critiqued an LCFS as being uneconomical. Specifically, one 

expert stated that, while an LCFS such as the one in California could 

force technology and create greenhouse gas reductions in the fuel 

market, the costs of implementing an LCFS are much higher than its 

benefits.

 25For example, the California Low Carbon Fuel Standard requires a 10-percent reduction 

in the carbon intensity of fuels in the State of California by 2020. It requires fuel suppliers 

to reduce the expected lifecycle greenhouse gas emissions from motor fuels on the basis 

of the fuels’ energy content. In this way, the greenhouse gas intensity of transportation 

fuels decreases, regardless of the growth in transportation or fuel demand.
Page 21 GAO-17-94 Renewable Fuel Standard

We provided a draft of this product to EPA for comment. In its written 

comments, reproduced in appendix III, EPA generally concurred. EPA 

also provided technical comments, which we incorporated as appropriate.

As agreed with your office, unless you publicly announce the contents of 

this report earlier, we plan no further distribution until 30 days from the 

report date. At that time we will send copies to the appropriate 

congressional committees and to the Administrator of the EPA. In 

addition, the report will be available at no charge on the GAO website at 

http://www.gao.gov.

If you or your staff members have any questions about this report, please 

contact me at (202) 512-3841 or ruscof@gao.gov. Contact points for our 

Offices of Congressional Relations and Public Affairs may be found on 

the last page of this report. GAO staff who made key contributions to this 

report are listed in appendix IV.

Sincerely yours,

Frank Rusco

Director, Natural Resources and Environment

Agency Comments 

and our Evaluation
Appendix I: Scope and Methodology

Page 22 GAO-17-94 Renewable Fuel Standard

The objectives of this report were to provide information on (1) whether 

the Renewable Fuel Standard (RFS) is expected to meet its goals, (2) 

expert views on any federal actions that could improve the RFS 

framework, and (3) policy alternatives experts suggested to better meet 

the goals of the RFS in the future.

To address our objectives, we contracted with the National Academy of 

Sciences to provide us with a list of experts on issues related to the RFS, 

including the current structure of the RFS; blending, distribution, and 

marketing infrastructure of biofuels; automobile manufacture; and 

petroleum consumption and prices. The National Academy of Sciences

identified 25 experts, including experts from academia and policy think 

tanks and practitioners with relevant experience.1 Areas of expertise 

included policy analysis of the RFS, first-hand knowledge of the 

production and distribution of biofuels and flex fuel vehicles, and the 

economic and environmental ramifications of the RFS. We conducted 

semistructured interviews and performed a content analysis of the 24 

experts’ responses to our questions. For reporting purposes, we 

categorized expert responses as follows:

• “nearly all” experts represents 21 to 23 experts,

• “most” experts represents 16 to 20 experts,

• “many” experts represents 11 to 15 experts,

• “several” experts represents 6 to 10 experts, and

• “some” experts represents 2 to 5 experts.

See appendix II of this report for a list of experts whose names were 

provided by the National Academy of Sciences.

We also reviewed public comments from stakeholders, relevant 

legislation, and agency documents pertaining to annual volume 

requirements (e.g., the Environmental Protection Agency’s (EPA) 

response to public comments) and conducted a literature search for 

research related to the RFS. In addition, we interviewed officials at EPA, 

the Department of Energy (DOE), and the Department of Agriculture 

(USDA). We also interviewed Congressional Research Service officials 

who have conducted extensive work on the RFS. To provide expert views 

 1

We could not reach one of the experts provided by the National Academy of Sciences. 

After determining that this expert’s absence would not affect the balance of the group, we 

removed him from our expert list.

Appendix I: Scope and Methodology
Appendix I: Scope and Methodology

Page 23 GAO-17-94 Renewable Fuel Standard

on actions needed to address these challenges and meet the goals of the 

RFS in the future, we used our content analysis of the experts’

responses, which identified possible actions within the current RFS 

structure, changes to the RFS structure, and through policy alternatives to 

the RFS. Finally, this report drew from a companion report, GAO-17-108, 

that examined federal research and development in advanced biofuels 

and related issues.2

We conducted this performance audit from June 2015 to November 2016 

in accordance with generally accepted government auditing standards. 

Those standards require that we plan and perform the audit to obtain 

sufficient, appropriate evidence to provide a reasonable basis for our 

findings and conclusions based on our audit objectives. We believe that 

the evidence obtained provides a reasonable basis for our findings and 

conclusions based on our audit objectives.

 2

GAO-17-108. 
Appendix II: List of Experts’ Names Provided 

by the National Academy of Sciences

Page 24 GAO-17-94 Renewable Fuel Standard

Table 1: List of Experts’ Names Provided by the National Academy of Sciences

Name Affiliation

Bruce Babcock Iowa State University

David Babson Union of Concerned Scientists

John Caupert National Corn to Ethanol Research Center

Joseph M. Colucci Automotive Fuels Consulting, Inc.; General Motors 

Research and Development Center (retired)

John DeCicco University of Michigan Energy Institute

Harry de Gorter Cornell University

Matthew Forman Fiat Chrysler 

Barry Frazier Center Oil Company

Jeff Gallic Thorntons Inc.

Jason Hill Institute on the Environment, University of Minnesota

Scott H. Irwin University of Illinois

Madhu Khanna Institute for Sustainability, Energy and Environment, 

University of Illinois, Urbana-Champaign

Ron Minsk Center on Global Energy Policy

John Miranowski Iowa State University

Steffen Mueller Energy Resources Center, University of Illinois at 

Chicago

Sebastien Pouliot Iowa State University

Jonathan Rubin University of Maine

Benjamin Salisbury FBR Capital Markets

Dan Sperling University of California, Davis

James H. Stock Kennedy School, Harvard University

Stephanie Searle International Council on Clean Transportation

Jim Sweeney Stanford University

Wallace E. “Wally” Tyner Purdue University

Wallace “Wally” R. Wade Ford Motor Company (retired)

Source: National Academy of Sciences. | GAO-17-94

Appendix II: List of Experts’ Names Provided 

by the National Academy of Sciences
Appendix III: Comments from the 

Environmental Protection Agency

Page 25 GAO-17-94 Renewable Fuel Standard

Appendix III: Comments from the 

Environmental Protection Agency
Appendix III: Comments from the 

Environmental Protection Agency

Page 26 GAO-17-94 Renewable Fuel Standard
Appendix III: Comments from the 

Environmental Protection Agency

Page 27 GAO-17-94 Renewable Fuel Standard
Appendix IV: GAO Contact and Staff 

Acknowledgments

Page 28 GAO-17-94 Renewable Fuel Standard

Frank Rusco, (202) 512-3841 or ruscof@gao.gov.

In addition to the individual named above, Karla Springer (Assistant 

Director), Jessica Artis, and Jarrod West made key contributions to this 

report. Luqman Abdullah, Richard Burkard, Cindy Gilbert, Robert Keane, 

Scott McClinton, Cynthia Norris, and Dan Royer also made important 

contributions.

Appendix IV: GAO Contact and Staff 

Acknowledgments

GAO Contact

Staff 

Acknowledgments

(361642)
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