Fact Sheet April 2005

Low-Level Ethanol Fuel Blends 

the reduction of CO can be significant (20% to 30%). 

Emissions of NOx are not increased through the use of 

low-level blends because the 3-way catalytic converter 

ensures that tailpipe emissions comply with NOx

standards. In addition, by displacing gasoline, ethanol 

reduces exposure to toxic pollutants found in gasoline.

E10 has a higher vapor pressure than does gasoline, which 

gives the fuel a higher volatility. This increased volatility 

can cause higher evaporative emissions of light hydrocarbon from the fuel. However, state and federal regulations 

control the volatility of the blended fuel. Higher vapor 

pressure can also cause permeation through fuel system 

components, although this is expected to decrease as fuel 

systems continue to meet new standards for evaporative 

emissions.

The use of ethanol blends significantly reduces the emission of greenhouse gases. In the United States, ethanol 

is made from agricultural crops, predominantly corn. As 

it grows, the corn plant captures carbon dioxide from the 

atmosphere, converting it to sugars and starches through 

photosynthesis. These sugars and starches are then 

fermented to produce ethanol, transforming the building 

blocks of a potent greenhouse gas to a renewable fuel. 

Fuel Performance and Availability 

There have been many successful years of vehicle operating experience with low-level ethanol blends. All auto 

manufacturers warranty their vehicles to operate on E10 

or less. Ethanol has higher octane than gasoline, leading 

to excellent drivability and performance. Ethanol has less 

energy content per gallon than does gasoline, but at blends 

of E10 and below, there is typically not a perceptible 

difference in fuel economy or range. 

The U.S. Department of Energy’s (DOE) Clean Cities 

initiative supports the use of blends of ethanol with 

gasoline as one of a range of technologies and strategies 

that can reduce our nation’s reliance on imported petroleum for transportation. Ethanol is made from renewable 

resources grown on our nation’s farms. Using ethanol 

blends in gasoline reduces our consumption of petroleum 

and supports local and regional economies.

Ethanol is being used today in blends ranging from 5% 

to 85%. Blends of up to 10% ethanol with gasoline (E10) 

are approved for use in all gasoline vehicles, and have 

been used for many years across the nation to improve 

air quality. 

Blends above 10% require use of flexible-fuel vehicles 

(FFVs), which are sold as standard models by several 

automakers. These vehicles have special controls and 

materials to accommodate higher levels of ethanol. More 

than 4 million FFVs are on the road today, and these 

vehicles can use any proportion up to 85% ethanol with 

gasoline. The most popular higher blend is E85, currently 

available at more than 200 stations. Retail fueling stations 

for this U.S.-produced fuel are growing at a steady pace, 

especially in the Midwest. To find station locations, see 

the Alternative Fuels Data Center’s Station Locator at 

www.eere.energy.gov/afdc/infrastructure/locator.html. If 

you’re not sure if your vehicle can accept E85, look inside 

your gas cap or in your owner’s manual.

Both E85 and lower-level blends can have a place in local, 

state, or regional transportation systems. The large number 

of FFVs in fleets and those owned by consumers are ready 

markets for new E85 infrastructure, while users of E10 or 

below can take advantage of the broader vehicle stock and 

the existing fueling infrastructure. This fact sheet focuses 

on the performance, emissions, and opportunities of E10 

or lower; see the Clean Cities publication Do You Own a 

Flexible Fuel Vehicle? for more information on FFVs 

and E85.

Vehicle Emissions

Ethanol has been used in vehicles since the early 1990s to 

promote more complete combustion of the fuel, thereby 

reducing emissions of carbon monoxide (CO), a regulated 

pollutant that is dangerous to human health. Particularly 

in cold weather with older or poorly maintained vehicles, 

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Ethanol Production 1999-2004

Source: Renewable Fuels Association
Clean Cities

to support ethanol development from state resources. 

(See www.ncsl.org/programs/energy/ethinc.htm.)

What Clean Cities Coalitions Can Do

Some states are aggressively pursuing more widespread 

use of ethanol in their public fleets, or in the retail fuel 

supply. For example, Minnesota requires almost all 

gasoline sold within the state to contain 10% ethanol. 

Other states are considering similar initiatives.

Clean Cities coalitions can work with state regulators and 

legislators to encourage policies that require use of E10 

or less. Partnerships can often be formed with the agricultural community to help build support for these policies. 

Through Clean Cities, coordinators can access comparative information about other states’ programs and technical information about ethanol issues to help ensure new 

state programs are successful.

Coordinators can also work with nearby federal, state, 

and utility fleets to encourage use of ethanol blends. 

Many of these fleets have extra motivation to use 

regionally produced fuels, and in some cases, are 

required to do so by federal regulations.

Public education can also help build support for these 

homegrown fuels, which can contribute to local and 

regional economies.

The supply of ethanol is steadily growing. According to 

the Renewable Fuels Association, the ethanol industry 

produced about 3.4 billion gallons in 2004, up from 

2.81 billion gallons in 2003, a 21% increase. In February 

2005, DOE/EERE’s Biomass Energy Program estimated 

that U.S. agricultural and forest resources could potentially meet 30% of our current transportation fuel needs. 

Currently, 98 ethanol plants nationwide have the capacity 

to produce nearly 3.7 billion gallons annually. There are 

17 ethanol plants under construction with a combined 

annual capacity of more than 689 million gallons.1 Local 

economic development is often a driver for these new 

plants, along with increased expected demand.

Infrastructure for production and distribution of ethanol 

blends varies regionally around the country. Areas that have 

been using ethanol as an oxygenate have well-established 

infrastructure. As methyl tertiary butyl ether (MTBE) is 

phased out as an oxygenate because of groundwater concerns, ethanol infrastructure will likely expand to other 

regions of the country.

In the coming years, ethanol will be produced from other 

materials besides corn. DOE and industry are developing 

technologies to produce ethanol from farm and forestry 

materials such as cornhusks and stalks, grasses, and fastgrowing trees. The first ethanol production plants to use 

this technology are expected to be built starting in 2008.

Cost, Incentives, and Regulations 

Prices at the pump for E10 are competitive with gasoline 

prices. Production costs for ethanol, currently more expensive than for gasoline, are subsidized by about $0.50 per 

gallon of ethanol, taken as a tax credit by blenders. Legislation passed by Congress in 2004 modified the ethanol tax 

incentive, making it easier for blenders to use this credit, 

although the Internal Revenue Service is still developing 

rules to implement the changes. The most current status 

of this rulemaking can be found at the Renewable Fuels 

Association Web site: www.ethanolrfa.org/VEETC.htm.

Technical and financial assistance is available for developing ethanol production facilities through the U.S. Department of Agriculture. (See www.ethanolrfa.org/leg_ 

position_usda.shtml.) Several states also have programs 1 Renewable Fuels Association press release, “U.S. Ethanol Industry Sets Annual 

 Production Record of 3.4 Billion Gallons in 2004”, February 23, 2005

Resources for Additional Information

Clean Cities Resources:

• Clean Cities Fuel Blends Web site: 

www.eere.energy.gov/cleancities/blends

• Alternative Fuels Data Center

www.eere.energy.gov/afdc

• National Alternative Fuels Hotline

800-423-1363

National Ethanol Vehicle Coalition (NEVC) www.e85fuel.com

Renewable Fuels Association (RFA) www.ethanolrfa.org

Governors’ Ethanol Coalition www.ethanol-gec.org

For more information about Clean Cities visit www.eere.energy.gov/cleancities

Prepared by the National Renewable Energy Laboratory (NREL)

NREL is a U.S. Department of Energy National Laboratory

Operated by Midwest Research Institute • Battelle

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Energy efficiency and clean, renewable energy will mean a stronger economy, 

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DOE/GO-102005-2028 • April 2005