EPA420-S-08-001

January 2008

Compliance and Innovative Strategies Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

Fuel Trends Report: 

Gasoline 1995 - 2005

Executive Summary
iii

Executive Summary

This report presents 1995-2005 clean fuel programs implementation data collected

and analyzed by the Environmental Protection Agency’s (EPA’s) Office of Transportation and

Air Quality. The data show that significant changes in gasoline composition during this

period resulted in emission reductions often substantially greater than regulatory

requirements. Future reports on fuel trends will be issued periodically.

Background

As a result of the Clean Air Act (CAA) of 1990, EPA adopted clean fuel programs for gasoline. In

1995, EPA implemented the Reformulated Gasoline (RFG) program, designed to reduce emissions of

ozone-causing volatile organic compounds (VOCs) and oxides of nitrogen (NOx), and air toxics such as

benzene and formaldehyde. At the same time, EPA implemented an anti-dumping program, to protect

the emission qualities of conventional gasoline (CG). In 2000, credit for early gasoline sulfur reduction

was provided by EPA’s Tier 2 gasoline sulfur program.

These clean fuel programs required gasoline refiners and importers to analyze gasoline, measure

certain emission-related parameters, and submit the data to EPA. These data have limitations, but in

many respects, provide an unparalleled source of information about gasoline property trends since 1995.1

Key Findings

 Gasoline Sulfur Decreases -- Average annual sulfur content in all gasoline dropped from about

300 ppm in 1997 to about 90 ppm in 2005.

 RFG NOx Reductions Exceed Requirements -- RFG exceeded applicable NOx performance

standards during both Phase I (1998-1999) and Phase II (2000 and beyond).

 RFG Toxics Reductions Exceed Requirements -- On average, Phase I RFG complied with

Phase II standards, and toxic performance still improved with the transition to Phase II

standards.

 Conventional Gasoline NOx and Toxics Emissions Decreased -- Between 1998 and 2005,

the summer NOx emissions of conventional gasoline were reduced by 5.7 percent, while summer

exhaust toxics were reduced by 4.7 percent.

 Ethanol Use in RFG Increased and MTBE Use Decreased -- In the summer of 1996, about

11 percent of the RFG sold contained ethanol while virtually all the remainder contained MTBE.

By the summer of 2005, the ethanol share increased to about 53 percent, with corresponding

decreases in MTBE.

Gasoline Sulfur Decreases

As Figure 1 demonstrates, average annual sulfur content in all gasoline dropped from about 300

ppm in 1997 to about 90 ppm in 2005. Early decreases in overall gasoline sulfur content were primarily

due to decreases in RFG sulfur content linked to the phase-in of increasingly stringent RFG NOx emission

performance standards. These NOx emission performance standards did not mandate sulfur reduction,

but lowering sulfur content was one of several property changes important to meeting the RFG NOx

standards. Post-2000 decreases were also due to early Tier 2 sulfur reductions, applicable to both RFG

1

EPA lacks information about certain properties, and has only partial information on others. One important

limitation of the trend analyses in this report is that, with the exception of certain oxygen and oxygenate analyses,

they do not include California gasoline.
iv

and CG. Phase-in of Tier 2 sulfur reductions began in 2004, but credit generation for early sulfur

reduction was allowed beginning in 2000.

Figure 1

RFG NOx Reductions Exceed Requirements

As Figure 2 demonstrates, RFG exceeded applicable NOx performance standards during both

Phase I (1998-1999) and Phase II (2000 and beyond). The summer NOx performance of Phase I RFG

exceeded the standard by as much as 3.5 percent, while the summer NOx performance of Phase II RFG

exceeded the standard by as much as 4.1 percent.

Annual Average Gasoline Sulfur Content - (parts per million)

Estimated from EPA Reporting System Data

0

50

100

150

200

250

300

350

1997 1998 1999 2000 2001 2002 2003 2004 2005

Year

Sulfur (ppm)

All Gasoline

RFG

CG
v

Figure 2

RFG Toxics Reductions Exceed Requirements

RFG also exceeded toxics performance standards. As Figure 3 demonstrates, the summer toxics

performance of Phase I RFG exceeded the standard by as much as 15.1 percent, while the summer toxics

performance of Phase II RFG exceeded the standard by as much as 12.8 percent. Winter RFG toxics

performance also exceeded standards (See Figure 9 in the RFG Trends section). On average, Phase I

RFG complied with Phase II standards, and toxic performance still improved with the transition to Phase

II standards.

Figure 3

NOx Performance of Summer RFG-Estimated from EPA Data

(Based on Phase II Complex Model)

0

2

4

6

8

10

12

1998 1999 2000 2001 2002 2003 2004 2005

Year

% Emi ssion Reduction (from baseline gasoline)

Retail Avg.

Reporting Avg.

Phs II Averaged Std

Phs I Averaged Std *

*Phase I standard is an

approximation

based on the Phase II

complex model

Toxics Performance of Summer RFG - Estimated from EPA Data

(Based on Phase II Complex Model)

0

5

10

15

20

25

30

35

40

1998 1999 2000 2001 2002 2003 2004 2005

Year

% Emission Reduction (from baseline gasoline)

Retail Avg.

Reporting Avg.

Phs II Averaged Std

Phs I Averaged Std *

*Phase I standard is an

approximation

based on the Phase II

complex model
vi

Conventional Gasoline NOx and Toxics Emissions Decreased

As Figures 4 and 5 demonstrate, between 1998 and 2005, the summer NOx emissions of

conventional gasoline were reduced by 5.7 percent, while summer exhaust toxics emissions were reduced

by 4.7 percent. Winter emissions also decreased during this period (See Figures 3 and 5 in the

Conventional Gasoline Trends section). These reductions were not required by EPA regulations; instead,

they were a byproduct of Tier 2 sulfur regulation.

Figure 4

Figure 5

NOx Emissions of Summer CG

Estimated from EPA Reporting System Data

1200

1220

1240

1260

1280

1300

1320

1340

1998 1999 2000 2001 2002 2003 2004 2005

Year

Milligrams per Mile

Exhaust Toxics Emissions of Summer CG

Estimated from EPA Reporting System

Data

66

67

68

69

70

71

72

73

74

75

1998 1999 2000 2001 2002 2003 2004 2005

Year

Milligrams per Mile
vii

Ethanol Use in RFG Increased and MTBE Use Decreased

The CAA required that RFG contain two percent oxygen by weight. MTBE and ethanol were the

primary oxygenates used. Figure 6 shows the increasing use of ethanol in RFG and the decreasing use of

MTBE through 2005. In the summer of 1996, only about 11 percent of the RFG sold contained ethanol

while virtually all the remainder contained MTBE. By the summer of 2005, the ethanol share increased to

about 53 percent, with corresponding decreases in MTBE use.

% of Summer RFG Oxygenated with Ethanol and Ethers (Including Federal RFG Areas in CA)

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Ethanol 11% 10% 11% 12% 12% 15% 18% 37% 54% 53%

MTBE TAME other 89% 90% 89% 88% 88% 85% 82% 63% 46% 47%

1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Figure 6

Gasoline oxygen content has been a topic of considerable interest. Concerns over groundwater

contamination from MTBE resulted in various state laws banning or phasing out its use in gasoline. The

Energy Policy Act of 2005 included a renewable content requirement for gasoline and eliminated the RFG

oxygen content requirement. RFG data for 2006, while not analyzed for this report, show that RFG

suppliers continued to use oxygen in RFG even after the requirement was removed in May of 2006, and

that virtually all of this RFG was ethanol-oxygenated. MTBE use in RFG is currently at near zero levels.

EPA finalized Renewable Fuel Standard program regulations in April 2007 to implement the Energy Policy

Act renewable content requirement. Like RFG, these regulations include new recordkeeping and

reporting requirements designed to track the volume of renewable fuel, including ethanol.