The San Joaquin Valley Air Board in California is blocking development of methane digesters by demanding near-perfect air quality from engines. The mandated emission standard of 9 parts per million nitrogen oxide (NOx) has never been demonstrated scientifically, says Allen Dusault, director of sustainable agriculture at Sustainable Conservation. Engines available can only achieve 30 to 40 parts per million NOx. "Installing additional control equipment, to meet the Air Board's standard would cost dairies another $300,000 to $400,000, which is more than the engine itself costs, and it threatens to kill new projects," says Dusault. Already half a dozen projects in the pipeline are stalled because of the Air Board’s stance.  Aug. 13, 2008 Dairy Herd Management