Humboldt State University

Schatz Energy Research Center

Torrefaction

Hands holding wood chips before and, much darker in color, after torrefaction.

During 2010-2012, SERC worked in partnership with Renewable Fuel Technologies of San Mateo, CA to develop, test, and commercialize a biomass torrefaction system. We operated RFT’s prototype torrefier in our outdoor lab area for several months. The torrefier is capable of producing five pounds per hour of torrefied wood.

Torrefaction is a mild form of pyrolysis in which biomass is heated in an inert environment to a temperature between 200 and 300 °C. During the process, water and volatiles are removed and the hemicelluloses break down, yielding a dry, blackened solid product with a lower moisture content and higher energy content on a mass basis than the initial biomass. Torrefied biomass can be co-fired with coal or made into fuel pellets, fireplace logs, or barbeque briquettes for residential use.

RFT’s torrefier also captures the energy-rich gases given off by the biomass during torrefaction. These torrgases can be used to produce all the heat and electric power needed to drive the torrefier, thus making it a stand-alone device and able to process wood in remote forest locations where no utility power is available. Using outcomes from SERC’s testing of the prototype, RFT plans to build a much larger, pre-commercial torrefier with an output capacity of 25 tons per day.

A group of people view a demonstration of a prototype torrefier unit at SERC.

For more detailed information on SERC’s torrefaction work, see the following stories from past issues of SERC Energy News: