Biomass-to-Liquids Production

Currently, the major biomass-to-liquids production processes are gas-to-liquids conversion and pyrolysis. Both processes employ heat and chemical reactions to convert biomass into fuels, chemicals, and power. The products of both processes are cleaner and more efficient than the solid biomass from which they were derived. Another benefit is that biomass-to-liquids processes can convert types of biomass, such as wood and agricultural residues, that are difficult to handle using other biofuel production processes.

Gas to Liquids

In the first step of this process, biomass is turned into a gas by heating it in the presence of about one third of the oxygen necessary for complete combustion. The result is a mixture of carbon monoxide and hydrogen called synthesis gas or syngas. Syngas can be burned directly to produce electricity or converted into hydrocarbons (such as gasoline and diesel), alcohols, ethers, or chemical products.

The petroleum and petrochemical industries have developed commercial processes for converting syngas into fuels and chemicals, including the Mobil Methanol-to-Gasoline process, methanol synthesis, hydrocarbon fuels synthesis, and hydrogen synthesis. One of the most important processes is Fischer-Tropsch synthesis. This process has been demonstrated on a large scale for producing liquid transportation fuels from fossil fuels such as natural gas and coal; biomass also could be used as a Fischer-Tropsch feedstock, alone or in conjunction with fossil fuel sources.

There are currently no commercial biomass gas-to-liquids producers. Companies such as Syntroleum are considering commercial biomass-based projects.

Pyrolysis

In this process, biomass is heated in the absence of oxygen to produce a liquid pyrolysis oil—sometimes called bio-oil—which can be burned like fuel oil or refined into chemicals and fuels.

Several commercial facilities produce energy and chemicals from pyrolysis oil. Upgrading pyrolysis oil to high-quality hydrocarbon fuels has been demonstrated at a non-commercial scale.

To learn more about biomass-to-liquids production, see the U.S. Department of Energy Biomass Program's information on thermochemical conversion.