Cellulosic Ethanol: What to Do with the Lignin

Biomass Magazine August 2009
By Bruce Folkedahl

Lignocellulosic ethanol production has been a goal of the U.S. DOE for some time, and yet it remains at least a few years off as a demonstrated viable technology. Lignocellulosic biomass can be converted to ethanol through either a biochemical or thermocatalytic process. The biochemical process utilizes several pretreatment and hydrolysis steps to rupture the lignin walls surrounding the cellulose and hemicellulose fibers. This makes these fibers available for fermentation to ethanol. This process always leaves about 15 percent to 30 percent of the input biomass mass as unconverted lignin, a complex polymer found in most plant material. Lignin poses either a potential disposal liability or a byproduct opportunity.

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