By John Carey

The U.S. is desperate to wean itself from imported oil. Toward that end, it has mandated that by 2010, U.S. fuel consumption must include 100 million gallons of "advanced" biofuels that don't depend on corn, sugarcane, or other food crops as feedstock. And by 2022, that mandate rises to 21 billion gallons per year. Typically, that means using heat, acid, or enzymes to break up the cellulose in plant matter—everything from switchgrass and corn husks to wood chips and paper trash—then fermenting the mixture into "cellulosic ethanol." This is more difficult than simply fermenting starches and sugar into ethanol, a process humankind mastered eons ago. So difficult, in fact, that experts say America's budding biofuel industry can't possibly meet its ambitious short-term targets. Nevertheless, scores of biotech startups have jumped into the game, sometimes partnering with big oil companies that also have their eyes on the government mandates. Here's a look at some of the most promising ventures.

Business Exchange related topics:
Ethanol
Business of Biotechnology
Renewable Energy