General Motors (NYSE: GM) announced this weekend at the North American International Auto Show in Detroit that it would partner with Coskata Inc., an Illinois-based renewable energy start-up company that plans to produce ethanol from agricultural, municipal, and industrial waste byproducts.

"GM is enabling Coskata to produce the next generation of biofuels -- without using a food source -- making it economically viable and commercially available," said Coskata CEO Bill Roe. "Alternative transportation fuels are coming faster than people think ... and will be available at a lower cost than people have imagined."

Coskata is backed by billionaire investor Vinod Khosla, said the Wall Street Journal, and is one of a handful of ethanol makers in the U.S. that are trying to develop a method for efficiently producing cellulosic ethanol.

But Coskata's cellulosic ethanol won't be available at retail gas stations until 2010 or later. The company maintains that its process is commercially viable already. It plans to open a 40,000-gallon demonstration facility by the end of this year to deliver ethanol to GM for vehicle testing, before building a 100-million-gallon commercial plant at an undetermined U.S. location.

GM's foray into the cellulosic ethanol field is part of a broader campaign to convince car buyers that it is committed to fuel economy and capable of competing with Toyota Motor Corp. (NYSE: TM) in terms of environmental leadership. GM's stake in the partnership with Coskata was undisclosed.