Edited by Stephen J. Mraz

The rule of thumb was that for every unit of energy put into the process, you got out ethanol with about 1.3 units of energy. A fermentation process refined by engineers at Coskata, Warrenville, Ill. (coskata.com), a business partner with General Motors, is said to extract about 7 units of energy for every unit spent refining vegetation or feedstock into ethanol. It relies on proprietary microorganisms that eliminate the need for costly pretreatments with enzymes. The microorganisms also ferment the material at lower temperatures and pressures, which reduces operating and infrastructure costs. The resulting fuel should cost about $1/gallon. The process converts a dry ton of feedstock into about 100 gallons of 99.7% pure ethanol.