For Higher Biofuel Yields, An Old Technique Shows Promise

One thing you gather while covering the ever-lurching-forward cellulosic ethanol story (saga might be a better term) is that there is a hell of a lot of money behind it. How else to explain the parade of research papers – not to mention government-backed private initiatives – that arrive month after month, all suggesting some fab new way to turn nonfood biomass into fuel?

The latest arrives from researchers at Lawrence Berkeley National  Laboratory, aka Berkeley Lab, where a fermentation process used in World War I to make cordite for bullets and artillery shells has been recruited to the task of turning stuff that grows cheaply and isn’t meant to be eaten into fuel.

biofuel cellulosic ethanol

image via Wikimedia Commons

The scientists, working through the BP-backed Energy Biosciences Institute, say they used the bacterium Clostridium acetobylicum in the fermentation of the sugars in lignocellulosic biomass (this is basically the woody material of a plant; there’s plenty of lignocellulosic biomass out there, which makes it an attractive fuel source, but unlike starchy food feedstocks such as corn, it’s tricky getting at the sugars).

C. acetobutylicum, according to the Berkeley Lab, “rose to prominence during World War I when it was used by the British to ferment acetone for the production of cordite, a propellant that replaced gunpowder.” Its use in such fermentation processes was swept aside in the middle of the 20th century by less costly petrochemical-based processes.

Anyway, this fermentation is a key step but only the first step in the Berkeley Lab process. The fermentation yields three parts acetone, six parts n-butanol, and one part ethanol. Having used biology to arrive there, the researchers then employ chemistry, using palladium to catalyze these shorter carbon chains into longer fuel chains.

“Many technologies today rely on either fermentation or chemical catalysis,” says Dean Toste, a chemist on the research team. “The idea of building integrated fermentation processes involving networks of catalysts is an exciting prospect.”

In some key ways, this sounds not a lot different, very broadly speaking, from what ZeaChem is at work on at its U.S.-backed demonstration plant in Oregon, which is expected to begin in the next month or so converting wheat straw and wood to make ethanol and chemical products; it talks of “using a hybrid combination of biochemical and thermochemical processing steps.”

ZeaChem says its scheme could raise ethanol yields by a big margin, as does the Berkeley Lab. Such outcomes would be a long time coming and sorely needed for cellulosic ethanol.

Under the Energy Independence and Security Act of 2007, the U.S. was supposed to produce 500 million gallons of cellulosic ethanol in 2012. The industry has been so laggard in getting off the ground, however, that the Environmental Protection Agency ended up setting the mandate for this year at 8.65 million gallons (and nobody thinks it will be met). Obviously, the outlook does not look good for meeting the long-term mandate of 16 billion gallons — that’s right, billion with a “b” — of the stuff by 2022.

The Obama administration has tried to give the sector a boost in the past year or so, approving loan guarantees for a couple of new plants in the Midwest – one in Kansas and another in Iowa– while continuing to shower largess on ZeaChem.

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.