Manure digesters clash with air quality requirements

Cracking down on methane labs: When animal manure decomposes, it releases methane, a greenhouse gas far more potent than carbon dioxide (on a mass basis). To avoid these emissions, some are installing manure digesters, in which bacteria convert the waste to methane gas. The methane is then burned in an internal combustion engine or a gas turbine to create electricity, resulting in a lower overall greenhouse gas emission rate and low-cost electricity. P.J. Huffstutter, the L.A. Times' new agriculture reporter, writes about how some California dairy cow operations have hit a major bump: air-quality agencies are refusing to give permits for the systems as they emit too much nitrogen oxide gas, which is a precursor to smog. California's dairy country has some of the worst air quality in the nation, so regulators are extra tough on any new sources of pollution. Unfortunately, this has caused trouble for some of the digester pioneers, who've had to upgrade their equipment or shut it down. As greenhouse gases begin to get a price (via laws like California's AB32) and as emission control technology improves, the situation will probably improve, because "California has about four times as much potential for emission reductions and energy generation as the next-largest dairy state," says EPA official Chris Voell. "I know the regulations are much more strict in California. But there's so much potential there." (Los Angeles Times)

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