Low natural gas prices have led food processors who hoped to harvest methane from their waste streams to rethink renewable energy projects. Each year has brought another precipitous drop in value: the spot price of natural gas averaged $8.86 per million Btus in 2008, the U.S. Energy Information Administration reports, and was selling for half that in 2010. Last year, the average spot price was $2.75/MMBtu.
In 2009, Chuck Ellis, president of Pearl Valley Cheese in Fresno, Ohio, ordered a 400,000-gallon anaerobic digester system from Siemens Water Technology to both lower BOD from cheese whey and wastewater streams and to produce methane to fire his plant's boiler. By the time the system was commissioned in 2011, We found that the ROI didn't pan out, he recalls.
On the other hand, Fresno's rural location in eastern Ohio (the community is approximately midway between Columbus and Pittsburgh) translates to high electric rates. Ellis accepted a bid from GEM Energy to engineer a high-pressure moisture removal system for methane to feed a 65 kW microturbine. The system came on line in March and is meeting about 20 percent of Pearl Valley's electric demand, feeding electricity back to the grid when the plant is not in production.