General Motors Corp. is taking an undisclosed equity share in Mascoma Corp., a Boston-based developer of cellulosic ethanol, AutoTech Daily reported Friday.

It’s the second such deal this year for GM, which invested in Warrenville, Ill.-based Coskata Inc. in January.

Coskata is working on a thermochemical process to make ethanol from non-grain sources. Mascoma is developing a single-step cellulose-to-ethanol method called consolidated bioprocessing. The process combines non-grain biomass with low-cost conversion techniques to make ethanol faster and cheaper than is possible with other biochemical methods that require more additives and enzymes, according to the company.

Mascoma is using proprietary microorganisms developed at its labs in Lebanon, N.H., and expects to begin producing ethanol later this year at a demonstration plant in Rome, N.Y. The company also has partnered with the University of Tennessee to develop a switchgrass-to-ethanol pilot facility near Knoxville and is planning a similar plant in Michigan to open in 2010. The company says a commercial-scale facility using its technology could yield 10 million gallons of ethanol per year.

Mascoma was founded in 2005 to pursue technology developed by researchers in Dartmouth University's Thayer School of Engineering. The privately held company is funded by venture capitalists and more than $60 million in state and federal grants.

GM says half the vehicles it makes for the U.S. market in 2012 will be able to run on a blend of 85 percent ethanol and 15 percent gasoline.