Companies tap into renewable natural gas markets

By Bryan Sims
Tarrytown, N.Y.-based Environmental Power Corp. and Canada-based QuestAir Technologies Inc. have been ramping up their respective renewable natural gas projects that utilize anaerobic digestion technology.

Environmental Power repaired and upgraded its Huckabay Ridge facility in Stephenville, Texas, and has resumed production of its trademarked pipeline-quality renewable natural gas (RNG). The company also resumed delivery of RNG to Pacific Gas & Electric Co. under a long-term power purchase agreement that runs through December 2018. Under the agreement, Environmental Power will pipe 8,000 million British thermal units (Btu) of RNG to the California-based utility company annually.

The Huckabay Ridge facility is owned and operated by Environmental Power subsidiary Microgy Holdings LLC. The plant, which started operation in January 2008, generates approximately 635,000 million Btu of RNG, enough to produce nine megawatts of electricity annually using manure from 10,000 dairy cows at local farms.

Meanwhile, QuestAir Technologies deployed its M-3200 pressure swing adsorption (PSA) systems for two international anaerobic digestion projects-one in Korea and the other in Austria-that will produce compressed natural gas (CNG) from biogas.

QuestAir's M-3200 PSA "is a modular biogas conditioning system that's skid-mounted for easy installation onto an existing anaerobic digestion operation," according to Andrew Hall, president and chief executive officer of QuestAir. "Basically, we just take the biogas that comes out of the digester and purify it into CNG, which can be converted into an alternative fuel, power or electricity," he said.

In addition to Korea and Austria, QuestAir's biogas purification systems are being employed in Ohio, California and Canada with more under development throughout the world, according to Hall.