Biomethane — Cow Power for Your Tank   Methane gas derived from dairy manure offers a substitute for natural gas to power motor vehicles. Known as biomethane, the odorless gas is entirely renewable and environmentally friendly, and can be produced locally. Switching to biomethane: Improves air quality Reduces greenhouse gas emissions Protects water quality Strengthens rural economies         As natural gas prices continue to rise, biomethane fuel is becoming cost-competitive with natural gas and diesel, and is much cheaper than hydrogen.   Biomethane's Potential There are 8.5 million cows in the United States, producing enough manure to potentially power about a million cars. California has particularly good reasons for using biomethane. The state is home to more than 1.7 million dairy cows that produce about 18 billion cubic feet of methane a year, equivalent to more than 150 million gallons of gasoline. Harnessing the methane from about 20% of California's cows could power all of the existing natural-gas-powered vehicles in the state. The San Joaquin Valley, where most of California's cows reside, has some of the nation's most polluted air. A dairy biomethane industry along Highway 99 could serve to launch a renewable fuel highway, possibly evolving in the future into a "hydrogen highway."

Proven Technology

The technologies for converting dairy manure to biomethane are already used at several landfills around the United States and elsewhere. Sweden has made significant investments in biomethane and is developing the capacity to meet 20% of its vehicle fuel demand with biofuels. Already, Sweden has 17 plants producing biomethane and runs 7,000 cars and buses on it.

Currently, methane digesters are used on some U.S. dairy farms to trap the methane released from cow manure and generate electricity. As a result of Sustainable Conservation's work with California dairy producers, 12 digests are now operating or under construction, which will generate about $1.6 million in electricity — enough to power 2,000 homes. This process will also help divert more than 400,000 tons of manure from 36,000 cows.

These methane digesters can be upgraded to convert dairy manure to biomethane, which can be used in place of natural gas to fuel buses and other vehicles. The future of biomethane depends larger on the willingness of the public and private sectors to invest in advancing the technology, infrastructure and public policy framework that can support large-scale biomethane production, distribution and use.

Sustainable Conservation's partners on the biomethane study, "Biomethane from Dairy Waste," included Western United Dairymen, Institute for Environmental Management, Great Valley Center, CalStart and RCM Digesters. The study was funded by a grant from U.S. Department of Agriculture.