Role of Biomass in Coal-to-Liquids

By Tony Snyder
The World Coal-to-Liquids (CTL) 2009 Conference held in Washington, D.C., in March truly lived up to its name, as representatives from six continents were in attendance. Several industry heavyweights presented updates on the latest in research and commercial development. To name a few, Shenhua Group, one of China's largest coal producers, presented information on the recent start-up of the world's first commercial-scale direct coal-to-liquid fuel plant in China. The plant will eventually be capable of producing 2,800 tons of synthetic fuels a day. ExxonMobil discussed its methanol-to-gasoline (MTG) technology that will be used in an indirect coal-to-liquids plant, which is slated to begin operation in China later this year.

A common theme mentioned by nearly all of the presenters was the potential impact that coal can have on the environment. Carbon dioxide (CO2) emissions have become a social and political hot-button issue, and the media and various environmental groups have painted coal in a less than favorable light. This was especially apparent at the conference as it was interrupted for nearly half an hour by environmental activists, who were protesting the continued use and development of coal as a source of energy and fuel.

These negative views are not entirely unsubstantiated, as historical CTL processes produced more than twice the amount of CO2 when compared with petroleum-derived fuel processes.

A partial solution to mitigate the potential environmental impacts of coal is carbon dioxide capture and storage. While it can be technically feasible to capture nearly all of the CO2 generated by a CTL process, it may be most economical or practical to capture some portion of the CO2. The feasibility and economics of CO2 sequestration are highly site-specific as well.

Lignocellulosic biomass-to-liquids (BTL) plants suffer from their own set of problems, not the least of which is the cost of transporting enough biomass to allow plants to take advantage of economies of scale. Cogasification of coal with biomass may be the final piece of the puzzle to make BTL and CTL commercialization environmentally and politically palatable. A study by the U.S. DOE National Energy Technology Laboratory determined that as little as 8 percent based on weight of biomass cogasified with coal-combined with carbon dioxide capture and storage-can significantly reduce the CO2 emissions.

A research report prepared by the Energy & Environmental Research Center in 2007 analyzed the potential synergies that can be found with the creation of domestic energy parks.

The pulp and paper industry, which already processes coal and biomass, provide ideal sites for the integration of fuel, heat and electricity production.

CTL fuel technology is rapidly being commercialized, particularly in China. If the social and political stigma currently placed on coal can be removed, perhaps CTL will be used to improve energy security in the United States and other nations as well. Biomass, along with carbon dioxide sequestration, may prove to be the key that unlocks the door.

Tony Snyder is a research engineer at the EERC. He can be reached at or (701) 777-6123.