October 25, 2005 | General

Biogas Replaces Natural Gas For Vehicles

BioCycle October 2005, Vol. 46, No. 10, p. 55
The technology reported in a new Sourcebook is described as “no cow-pie in the sky” solution – and California has the potential to produce the equivalent of 150 million gallons of gasoline.

Methane gas generated from dairy manure offers a substitute for natural gas that can power motor vehicles, reports a study released last month in California. Titled “Biomethane from Dairy Waste: A Sourcebook for the Production and Use of Renewable Natural Gas in California,” the study is a collaboration of energy, dairy and environmental groups. Known as biomethane, the gas is renewable, environmentally friendly, and can be produced locally.
The chapter on upgrading biogas to biomethane and other fuels in the Sourcebook includes these sections: Technologies for removal of hydrogen sulfide, water vapor, and carbon dioxide; Design for small dairy biomethane plant; Blending biogas with more valuable fuels; Converting biomethane to liquefied biomethane; and Environmental effects of gas cleanup technologies. A section on converting biomethane to noncryogenic liquid fuels features these topics: Methane-reforming and catalytic conversion processes; Biomethane to gasoline using the Fischer-Tropsch process; Biomethane to methanol; Biogas or biomethane to hydrogen fuel.
“There are 8.5 million cows in the United States, each producing enough manure to potentially generate about 30 cubic feet of biomethane per day, which could replace significant amounts of natural gas at today’s prices,” says Allen Dusault, Biofuels Project Manager for Sustainable Conservation, based in San Francisco. “If used as vehicle fuel, biomethane could power a million cars,” adds Dusault who spoke at this year’s BioCycle West Coast Conference.
“This is no ‘cow-pie in the sky’ solution,” explains Dusault. “Sweden has 20 plants producing biomethane and runs 2,300 buses on it. As natural gas prices continue to rise, biomethane fuel is becoming cost-competitive with natural gas and diesel, and is much cheaper than hydrogen. Switching to biomethane improves air quality, reduces greenhouse gas emissions, improves water quality and strengthens rural economies.”
Points out Paul Martin, Environmental Services Director of Western United Dairymen: “We’ll use the gas that forms when manure is processed in a methane digester and then upgrade to vehicle fuel quality. More than a dozen methane digesters are operating or under construction on dairy farms in California. Dairy farmers in New York, Wisconsin and other states are also discovering the economic, environmental and community benefits of locally produced energy.”
California has particularly good reasons for using biomethane. The state is home to more than 1.7 million dairy cows, with a technically feasible potential for producing about 18 billion cubic feet of methane a year, equivalent to over 150 million gallons of gasoline. The San Joaquin Valley, where most of the cows reside, has some of the nation’s most polluted air. A dairy biomethane industry along Highway 99 could serve as the start for a renewable fuel highway, possibly evolving in the future into a “renewable hydrogen highway.”
“Biomethane from Dairy Waste: A Sourcebook for the Production and Use of Renewable Natural Gas in California” represents a collaboration among experts from a wide range of specialties, including advanced transportation technologies, alternative fuels, dairy operations and environmental impacts. The study was funded by a grant from U.S. Department of Agriculture – Rural Development. Project partners include Sustainable Conservation, Western United Dairymen, Institute for Environmental Management, Great Valley Center, CalStart and RCM Digesters. This study is available at www.suscon.org.

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