The U.S. produces about 79 million tons of wet biomass annually, primarily in the form of food processing and animal wastes. These residues can be converted via hydrothermal liquefaction (HTL) to yield a biofuel with heating values comparable to that of petroleum crude.

The excessive water content and complex composition preclude the use of this biocrude as a transportation Researcher holds a sample of waste and a sample of distillate derived from biowaste. Source: L. Brian Staufferfuel. A solution devised at the University of Illinois entails combining distillation with esterification to upgrade HTL biocrude oil into diesel blendstock.

The biofuel derived from wet biomass is distilled into fractions with energy content similar to that of petroleum diesel. Distillate acidity is reduced through esterification, yielding a liquid fuel that can be blended with diesel and meets current diesel standards.

Engine tests performed using 10-20% upgraded distillates blended with diesel show 96-100% power output, 101-102% nitrogen oxides, 89-91% carbon monoxide, 92-125% unburned hydrocarbon and 109-115% soot emissions, compared with regular diesel.

A pilot-scale reactor now under construction can be mounted on a mobile trailer and produce 30 gallons a day of biocrude from one ton of biowaste.