Renewable Hydrocarbon Biofuels
Renewable hydrocarbon biofuels (also called "green" hydrocarbons, biohydrocarbons, drop-in biofuels, and sustainable or advanced hydrocarbon biofuels) are fuels produced from biomass sources through a variety of biological and thermochemical processes. These products are similar to petroleum gasoline, diesel, or jet fuel in chemical makeup and are therefore considered infrastructure-compatible fuels. They can be used in vehicles without engine modifications and can utilize existing petroleum distribution systems.
Types of renewable hydrocarbon biofuels include:
Renewable gasoline: Also known as biogasoline or "green" gasoline, renewable gasoline is a biomass-derived transportation fuel suitable for use in spark-ignition engines. It meets the ASTM D4814 specification in the United States and EN 228 in Europe.
Renewable diesel: Also called "green" diesel, renewable diesel is a biomass-derived transportation fuel suitable for use in diesel engines. It meets the ASTM D975 specification in the United States and EN 590 in Europe.
Renewable diesel is distinct from biodiesel. While renewable diesel is chemically similar to petroleum diesel, biodiesel is a mono-alkyl ester, which has different physical properties and hence different fuel specifications (ASTM D6751 and EN 14214). The two fuels are also produced through very different processes. While biodiesel is produced via transesterification, renewable diesel is produced through various processes such as hydrotreating (isomerization), gasification, pyrolysis, and other thermochemical and biochemical means. Moreover, biodiesel is produced exclusively from lipids (such as vegetable oils, animal fats, grease, and algae), whereas renewable diesel is produced from lipids and cellulosic biomass (such as crop residues, woody biomass, and dedicated energy crops).
Renewable jet fuel: Also called "biojet" or aviation biofuel, renewable jet fuel is a biomass-derived fuel that can be used interchangeably with petroleum-based aviation fuel. Certain biojet fuel can be blended up to 50% with conventional commercial and military jet (or aviation turbine) fuel by following requirements in the ASTM D7566 specification.
The following fuel categories are approved by the standard:
- Hydrogenated esters and fatty acids (HEFA) fuels derived from used cooking oil, animal fats, algae, and vegetable oils (e.g., camelina)
- Fischer-Tropsch fuels using solid biomass resources, e.g., wood residues.
- Synthetic iso-paraffin from fermented hydroprocessed sugar (SIP), formerly known as direct-sugar-to-hydrocarbon (DSHC) fuels. Only blends of up to 10% are permitted for this fuel
Other pathways, such as the alcohol-to-jet pathway, are also being evaluated for certification.
Renewable hydrocarbon biofuels 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 hydrocarbon biofuels. Production plants may be stand-alone or co-located at petroleum refineries.
Technology pathways explored for the production of renewable hydrocarbon biofuels include:
- Hydroprocessing of lipid feedstock
- Fermentation of sugars to hydrocarbons (more information is available from the National Advanced Biofuels Consortium [NABC])
- Catalytic conversion of sugars to hydrocarbons (more information is available from NABC)
- Upgrading of syngas (carbon monoxide and hydrogen) from gasification
- Pyrolysis or liquefaction of biomass to bio-oil with hydroprocessing
Currently, commercial-scale production of renewable hydrocarbon biofuels in the United States is limited. At the end of 2015, there were only two commercial facilities (Diamond Green Diesel in Louisiana and AltAir in California) with a combined capacity of 167 million gallons per year. Two other facilities (the Renewable Energy Group, Inc. in Louisana and KiOR in Mississippi) were fully constructed, but idled in 2015 due to market conditions or mechanical issues. Several demonstration and pilot plants are also operational. In addition to domestic production, the United States imports renewable hydrocarbon biofuels, primarily from Neste Corporation—the world’s leading producer of renewable diesel.
Renewable hydrocarbon biofuels offer many benefits, including:
Engine and infrastructure compatibility—Renewable hydrocarbon biofuels are similar to their petroleum counterparts and therefore minimize compatibility issues with existing infrastructure and engines.
Increased energy security—Renewable hydrocarbon biofuels 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 hydrocarbon biofuels.
More flexibility—Renewable hydrocarbon biofuels are replacements for conventional diesel, jet fuel, and gasoline, allowing for multiple products from various feedstocks and production technologies.
Research and Development
The National Advanced Biofuels Consortium, a U.S. Department of Energy (DOE) supported partnership of national laboratories, universities, and corporations, is working to make renewable hydrocarbon biofuels technologies cost effective and sustainable.
Another DOE-sponsored consortium, the National Alliance for Advanced Biofuels and Bioproducts, is developing technologies for a sustainable and commercially viable algal biofuels industry.
The DOE’s Bioenergy Technologies Office supports the development of design reports and case studies for various advanced technologies. Additional, more recent publications are also provided below.
- 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
In 2013, the U.S. Navy and the U.S. Department of Agriculture announced the Farm-to-Fleet program, which aims to increase the production of renewable hydrocarbon biofuels and their use in military applications while promoting rural economic development.
Learn more about renewable hydrocarbon biofuels 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
- Commercial Aviation Alternative Fuels Initiative
- The Feasibility of Producing and Using Biomass-Based Diesel and Jet Fuel in the United States
- Fungible and Compatible Biofuels: Literature Search, Summary, and Recommendations
- Production of Gasoline and Diesel from Biomass via Fast Pyrolysis, Hydrotreating, and Hydrocracking: A Design Case
- Hydrogenation-Derived Renewable Diesel
The AFDC also provides a publications search for more information.