Fiscalini then spent several hundreds of thousands of dollars on a catalytic converter and other filtering equipment to meet the air district's limit of 11 parts per million of NOx for new digester systems. That works out to equal the emissions of 26 cars for every 1,000 cows, said Frank Mitloehner, an associate professor at UC Davis' department of animal science.
But his worries are far from over. The digester has been running for only nine months, and he's already had to replace some of the filtering equipment and repair the generator twice.
"I wonder, sometimes, why I ever thought this was a good idea," Fiscalini said.
Air district officials said they're just doing their jobs. Combating smog, not climate change, is the agency's mission.
"The board has been clear that when we're faced with these sorts of trade-offs between reducing greenhouse gases and reducing NOx, we're going to choose NOx," said Dave Warner, director of permit services for the San Joaquin Valley air quality district.
The farmers "should have checked in with us first, before buying their equipment," he added.
Last year, six dairy digesters were shut down because of regulatory or financial problems. One of them is at Ron Koetsier's dairy in Visalia.
Koetsier had been using his digester and generator system since 2003 as a way to power his barns and eliminate his dairy's electrical bill. Southern California Edison, his electricity provider, had just opened the door in 2008 to buying his excess electricity when the San Joaquin Valley air district told him that his two generators violated local NOx emission standards for digesters.
He contacted the manufacturer of the generators. He said he was told that it would cost $100,000 in new parts to get them in compliance, and up to $50,000 a year in maintenance fees.
Koetsier shut the system down. Now the equipment is collecting dust.
"They have a point. I want clean air," Koetsier said. "But it doesn't make financial sense for me keep doing this. I don't see how they can turn methane gas into electricity in California, given these rules."