There are about 187 facilities in the United States that produce ethanol. The most common use of ethanol is as fuel ethanol in mixtures of motor gasoline, with smaller quantities used in industry as solvents or ingredients in the synthesis of organic chemicals. Most of the fuel ethanol produced in the United States is made by fermenting the sugar in the starches of grains such as corn, hence the term “corn ethanol.”
Not surprisingly, ethanol production capacity is highly concentrated in states in the Corn Belt, the area in the Midwest dominated by farming and agriculture, especially corn. About 50% of ethanol production capacity is in just three states: Iowa (27%), Nebraska (13%), and Illinois (10%). The largest ethanol plant in the country is operated by Marquis Energy in Hennepin, Illinois, with a capacity of about 400 million gallons of ethanol per year, or 2.3% of total national capacity in 2023.1
1 U.S. Energy Information Administration, “U.S. Biodiesel Plant Production Capacity,” August 7, 2023, https://www.eia.gov/biofuels/biodiesel/capacity/
Ethanol in the United States is primarily used as a fuel additive in gasoline. The most common blend is E10, which contains up to 10% ethanol mixed with 90% gasoline. Ethanol acts as an oxygenate that makes gasoline burn more completely, reducing tailpipe emissions of carbon monoxide and other pollutants. Ethanol has a high octane rating, which can increase the octane level of gasoline, improving engine performance.
E85 (or flex fuel) refers to high-level ethanol-gasoline blends containing 51% to 83% ethanol, depending on geography and season.1 E85 is used in a flex-fuel vehicle (FFV) which, as the name implies, has the flexibility of running on more than one type of fuel. FFVs can be fueled with unleaded gasoline, E85, or any blend of the two up to 83% ethanol. Depending on the actual ethanol content, E85 has less energy per gallon than gasoline to varying degrees (the impact on fuel economy lessens as the ethanol content decreases). Other than lower miles per gallon, motorists driving FFVs will see little difference when using E85 versus gasoline.2
E85 stations are heavily concentrated in states with large ethanol biorefinery capacity. Many Corn Belt states also have regulations and incentives to adopt FFVS. California’s Low Carbon Fuel Standard is designed to decrease the carbon intensity of California’s transportation fuel pool and encourages the use of E85 among a host of other renewable fuels.3 Several federal agencies have adopted FFVs to meet the requirement for low greenhouse gas-emitting vehicles.4
1 U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), “E85 (Flex Fuel),” accessed March 1, 2024, https://afdc.energy.gov/fuels/ethanol_e85.html
2 U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), “Ethanol Blends: Providing a Renewable Fuel Choice,” https://afdc.energy.gov/fuels/ethanol_e85_specs.html
3 California Air Resources Board, “Low Carbon Fuel Standard,” accessed March 1, 2024, https://ww2.arb.ca.gov/our-work/programs/low-carbon-fuel-standard
4 Government Accounting Office, “Federal Fleet Vehicles Agencies Have Continued to Incorporate Alternative, Fuel Vehicles into Fleets, but Challenges Remain,” GAO-19-397, July 2019, https://www.gao.gov/assets/710/700753.pdf
Biodiesel is produced in about 59 facilities in the United States. Biodiesel is a renewable, biodegradable fuel manufactured from vegetable oils, animal fats, or recycled restaurant grease. Like petroleum diesel, biodiesel is used to fuel compression-ignition (diesel) engines. Biodiesel can be blended and used in many different concentrations. The most common are B5 (up to 5% biodiesel) and B20 (6% to 20% biodiesel). B100 (pure biodiesel) is typically used as a blendstock to produce lower percentage blends and is rarely used as a transportation fuel.1
In 2020, soybean oil (72%), corn oil (13%), and canola oil (11%) are the dominant feedstocks in the production of biodiesel. Biodiesel plants are concentrated in the states where these feedstocks are produced. Many of those states also have regulations and incentives that encourage biodiesel production and consumption.
Renewable Biofuels operates the largest biodiesel production facility in North America at Port Neches, TX. The plant has access to a deep water port, and a major rail line, and is near major petroleum refineries. With a capacity of about 144,000,000 gallons of biodiesel per year, the port facility accounts for about 7% of total national production capacity.2
1 U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), “Biodiesel Fuel Basics,” accessed March 1, 2024, https://afdc.energy.gov/fuels/biodiesel_basics.html
2 Renewable Biofuels, accessed March 1, 2024, https://www.rbfuels.com/
The geographic distribution of biodiesel stations reflects proximity to biodiesel production facilities and state and federal policies that mandate or incentivize the use of biodiesel. In 2023, about 63% of all biodiesel stations were in three states: Illinois, Iowa, and Minnesota. This is intuitive because those states are major producers of soybean and other feedstocks for biodiesel.
But what about the large number of biodiesel stations in North Carolina? Various regulations and incentives require state-owned vehicles to shift to cleaner fuels such as biodiesel. As a result, Department of Transportation facilities in most counties in the state have biodiesel fueling stations that are not open to the public.
Renewable diesel is a fuel made from fats and oils, such as soybean oil or canola oil, and is processed to be chemically the same as petroleum diesel. Renewable diesel can be used as a direct substitute for conventional diesel (up to 100% or R100).
Renewable diesel and biodiesel are not the same fuel. Renewable diesel, previously known as green diesel, is a hydrocarbon produced most often by hydrotreating and via gasification, pyrolysis, and other biochemical and thermochemical technologies. Biodiesel is a mono-alkyl ester produced via transesterification.1 Biodiesel is used as a diesel blend stock in limited volumes (up to 20% or B20) rather than as a direct substitute for conventional diesel. Biodiesel can increase oxides of nitrogen (NOx) emissions in some engines – a characteristic that limits its blend level in diesel fuel.2
Seventeen renewable diesel plants were operating in the United States in 2023. The largest was the plant in Norco, Louisiana operated by Diamond Green Diesel LLC, with a capacity of nearly one billion gallons per year. The plant processes recycled animal fats, used cooking oil, and corn oil renewable diesel.3
1 U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy (EERE), “Renewable Diesel,” accessed March 1, 2024, https://afdc.energy.gov/fuels/renewable_diesel.html
2 California Air Resources Board, “Fact Sheet: Renewable Diesel Fuel Requirements,” accessed March 1, 2024, Link
3 Diamond Green Diesel, accessed March 1, 2024, https://www.diamondgreendiesel.com/
Nearly all renewable diesel is used in California due to economic benefits under the state’s Low Carbon Fuel Standard. The policy includes the In-Use Off-Road Diesel-Fueled Fleets Regulation whose goal is to reduce particulate matter (PM) and oxides of nitrogen (NOx) emissions from existing off-road heavy-duty diesel vehicles in California. The regulation covers a wide scope of vehicle types used in (but not limited to) industries as diverse as construction, air travel, manufacturing, landscaping, and ski resorts. Beginning January 1, 2024, all California fleets subject to this regulation are required to procure and only use R99 or R100 renewable diesel fuel in all vehicles subject to the Off‑Road Regulation, with some limited exceptions.1
1 California Air Resources Board, “Amendments to the In-Use Off-Road Diesel-Fueled Fleets Regulation,” August 29, 2023, Link
