USA BioEnergy uses its state-of-the-art, near-zero emission, carbon-based “wood waste” biomass-to-fuels technology for the USA BioEnergy, LLC biorefinery project in Texas. The technology has a highly efficient commercially well-proven gas-to-liquid (“GTL”) conversion system. It generates a near-zero sulfur, drop-in premium ASTM D975 diesel fuel or commercial and military grade jet fuel equivalent.
Making Liquid Fuel
USABE converts naturally occurring biomass to a gas via a process called gasification and that gas is then converted to a liquid via Fisher-Tropsch.
“Biomass, a renewable organic resource, includes agriculture crop residues (such as corn stover or wheat straw), forest residues, special crops grown specifically for energy use (such as switchgrass or willow trees), organic municipal solid waste, and animal wastes. This renewable resource can be used to produce hydrogen, along with other byproducts, by gasification.” (Source: energy.gov)
In the United States, there is more biomass available than is required for food and animal feed needs. A recent report projects that with anticipated improvements in agricultural practices and plant breeding, up to 1 billion dry tons of biomass could be available for energy use annually. For more information, see U.S. Billion-Ton Update: Biomass Supply for a Bioenergy and Bioproducts Industry.
Plants consume carbon dioxide from the atmosphere as part of their natural growth process as they make cellulose, off-setting the carbon dioxide released from producing hydrogen through biomass gasification and resulting in low net greenhouse gas emissions. (Source: energy.gov)
Combining Two Processes: Gasification and Fischer-Tropsch
Gasification is a process that converts organic or fossil-based carbonaceous materials at high temperatures without combustion, with a controlled amount of oxygen and/or steam into carbon monoxide, hydrogen, and carbon dioxide.
The Fischer–Tropsch Process
The Fischer–Tropsch process is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at temperatures of 150–300 °C (302–572 °F) and pressures of one to several tens of atmospheres. (Sources: wikipedia.org, sciencedirect.com)
The Fischer–Tropsch process was first demonstrated in Germany in the 1920s. It converts carbon monoxide and hydrogen into oils or fuels that can be substituted for petroleum products. The reaction uses a catalyst based on iron or cobalt and is fueled by the partial oxidation of coal or wood-based fuels such as ethanol, methanol, or syngas, typically coming from an adjacent gasifier. This process can produce “green diesel” or syngas, depending on the temperature and level of oxygen involved in the process.
Many refinements and adjustments to the technology have been made, including catalyst development and reactor design. Depending on the source of the syngas, the technology is often referred to as coal-to-liquids (CTL) and/or gas-to-liquids (GTL). Examples of current operating CTL plants include Sasol’s Sasolburg I and II plant, and an example of a GTL FT process is Shell’s plant in Bintulu, Malaysia. Several world-class GTL and CTL plants are currently at various stages of engineering, construction, and production in Nigeria, Qatar and China, and most recently in the United States as well.
The clean syngas leaving the gasification island is sent onto the FT synthesis island, where the clean shifted syngas is converted into primary products of wax, hydrocarbon condensate, tail gas, and reaction water. The wax is sent on to an upgrading unit for hydrocracking in the presence of hydrogen, where it is chemically split into smaller molecular weight hydrocarbon liquids. A hydrogen recovery unit is used to extract the required quantity of hydrogen from the tail gas as shown, or alternatively from the feed syngas stream.
The reaction products, along with that from the upgrading section, are fractionated into the final products of diesel, naphtha, and other light ends, depending on the desired product mix. The production facility is supported by several utility plants, including the power train.