Butanol—a promising next-generation biofuel—packs more energy than ethanol and can be shipped via oil pipelines. But, like ethanol, biobutanol production is focused on using edible feedstocks such as beets, corn starch, and sugarcane.
Now James Liao, a biomolecular engineer at the University of California, Los Angeles, has developed two routes to liberate butanol from its dependence on food crops. Liao, who has a track record for commercializing innovative biofuels processes, has proven that microbes can produce the advanced biofuel directly from agricultural wastes, as well as from protein feedstocks such as algae.
Liao’s demonstration of direct cellulose-to-butanol conversion could bring down the cost of cellulosic biofuels, which is currently prohibitively high. His protein-based process provides the biofuels field with entirely novel feedstock options.
While they’re renewable, biofuels face attacks from environmental and food activists, and biobutanol is no exception: the first generation of biobutanol plants under development will run on corn-based sugar and starch. “Butanol has some technical benefits, but the real problem is the amount of food that goes into making a gallon of fuel,” says Jeremy Martin, a senior scientist at the Union of Concerned Scientists, a Cambridge, Massachusetts-based advocacy group that is part of a broad coalition pushing Congress to end lucrative tax credits for corn ethanol.
Liao’s innovations could end biobutanol’s association with corn—an association that, ironically, is partly of his making. In 2008, Liao developed a microbial pathway for converting sugar into isobutanol, a high-octane isomer of butanol. That innovation is now being commercialized by Gevo, an Englewood, Colorado-based startup that Liao cofounded. Gevo raised $107 million in an IPO last month to support its plans to retrofit corn ethanol plants to produce isobutanol instead.
Plans for a shift to biofuels production from biomass feedstocks such as switchgrass, corn stalks, and sugarcane bagasse (or plant residue) are, meanwhile, moving slowly because of higher costs. The U.S. Environmental Protection Agency mandated use of just 6.6 million gallons of cellulosic ethanol this year—less than 3 percent of the 250-million-gallon goal set by Congress four years ago. The holdup is from added processing steps required to break down these cellulosic feedstocks and thus generate sugars for fermentation; the processing boosts costs considerably, making production facilities difficult to finance.
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