Design engineer Mike Sura programs a set of parameters into the 150 liter fermenter/bioreactor of the Project Horizon Demonstration Facility at Coskata's headquarters in Warrenville, Ill.

Companies typically operate in stealth mode when they want to vet their technology before having to explain it to the world. In ethanol producer Coskata’s case, the company wanted its process to be ready for the commercial market before it burst onto the scene. When the Warrenville-based company did let the world know it existed, it did so with the announcement of a major partnership with General Motors (NYSE: GM).

The auto giant had committed to converting half of its fleet to flex-fuel vehicles within the next five years and wanted to ensure that there would be enough ethanol to fuel those vehicles when it happened, according to Wes Bolsen, chief marketing officer at Coskata. After talking to several biofuels companies, GM invested an undisclosed amount of money in Coskata and became a part owner in the business, joining early investors Khosla Ventures, ATV, and Great Point Ventures. Now, GM is introducing Coskata to several Fortune 50 companies, hoping to set up the production capacity and distribution channels to make ethanol an easy choice at the pump.

Why Coskata over the dozens of other technologies out there? Primarily because the technology is here, working and scalable today, Bolsen says.

Coskata’s process revolves around a strain of proprietary microorganisms found in the early 2000s by University of Oklahoma professor Dr. Ralph Tanner. At the bottom of a lagoon on the university's campus, Tanner discovered a microorganism that essentially eats hydrogen and carbon monoxide and excretes ethanol.

Coskata scientists created a bioreactor that taps into the organism's biology: They feed a variety of feedstocks—old tires, trash, wood chips, switchgrass—into a gasifier to produce syngas, which is then pushed along a tube-like membrane. The microorganisms live on the outside it, and as gas moves down the middle, the microorganisms feed on the gas. It’s essentially a gas-to-liquid transfer: The microorganisms excrete ethanol into the watery environment around the membrane and Coskata captures the output.