Renewable gasoline (also called green or drop-in gasoline) is a fuel produced from biomass sources through a variety of biological, thermal, and chemical processes. The fuel is chemically identical to petroleum gasoline and meets the same ASTM D4814 specification. Renewable gasoline can be used in existing engines and infrastructure. Renewable gasoline is not a commercially used fuel in the U.S. at this time, as there is an emphasis on electrification of the light-duty market.
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 also via gasification, pyrolysis, and other biochemical and thermochemical technologies. It meets ASTM D975 specification for petroleum diesel. Biodiesel is a mono-alkyl ester produced via transesterification. Biodiesel meets ASTM D6751 and is approved for blending with petroleum diesel.
Renewable gasoline can be produced from various biomass sources. These include lipids (such as vegetable oils, animal fats, greases, and algae) and cellulosic material (such as crop residues, woody biomass, and dedicated energy crops). Researchers are exploring a variety of methods to produce renewable gasoline which include:
- Traditional hydrotreating—Used in petroleum refineries, hydrotreating involves reacting the feedstock (lipids) with hydrogen under elevated temperatures and pressures in the presence of a catalyst. Commercial plants currently use this technology.
- Biological sugar upgrading—This pathway uses a biochemical deconstruction process, similar to that used with cellulosic ethanol with the addition of organisms that convert sugars to hydrocarbons.
- Catalytic conversion of sugars—This pathway involves a series of catalytic reactions to convert a carbohydrate stream into hydrocarbon fuels.
- Gasification—During this process, biomass is thermally converted to syngas and catalytically converted to hydrocarbon fuels.
- Pyrolysis—This pathway involves the chemical decomposition of organic materials at elevated temperatures in the absence of oxygen. The process produces a liquid pyrolysis oil that can be upgraded to hydrocarbon fuels, either in a standalone process or as a feedstock for co-feeding with crude oil into a standard petroleum refinery.
- Hydrothermal processing—This process uses high pressure and moderate temperature to initiate chemical decomposition of biomass or wet waste materials to produce an oil that may be catalytically upgraded to hydrocarbon fuels.
Renewable gasoline offers many benefits, including:
Engine and infrastructure compatibility—Renewable gasoline is chemically identical and meets the same ASTM D4814 specification as petroleum gasoline, allowing its use in existing vehicles and infrastructure.
Increased energy security—Renewable gasoline can be produced domestically from a variety of feedstocks and contribute to U.S. job creation.
Fewer emissions—Carbon dioxide captured by growing feedstocks reduces overall greenhouse gas emissions by balancing carbon dioxide released from burning renewable gasoline. The California Energy Commission states that it can reduce carbon dioxide emissions by 61% to 83% depending on the feedstock used.
More flexibility—Renewable gasoline is a direct replacement allowing for multiple products from various feedstocks and production technologies.
Research and Development
The U.S. Department of Energy's (DOE) Bioenergy Technologies Office supports research, development, and analysis, as well as design cases (see the following) for renewable hydrocarbon fuels, including renewable gasoline.
- Biochemical Hydrocarbon Pathways
- Biological Conversion of Sugars
- Thermochemical Hydrocarbon Pathways
- In Situ and Ex Situ Pyrolysis
- Updated Fast Pyrolysis Design
- Algae Hydrocarbon Pathways
- Whole Algal Hydrothermal Liquefaction and Upgrading
Learn more about renewable gasoline from the links below. The Alternative Fuels Data Center (AFDC) and DOE do not necessarily recommend or endorse these companies (see disclaimer).
- Advanced Biofuels Association
- Production of Gasoline and Diesel from Biomass via Fast Pyrolysis, Hydrotreating, and Hydrocracking: A Design Case
- Neste is testing renewable gasoline in Sweden: Production of Gasoline and Diesel from Biomass via Fast Pyrolysis, Hydrotreating, and Hydrocracking: A Design Case
The AFDC also provides a publications search for more information.