But the cows there weren't just creating stink (and millions of gallons of milk) -- they were also producing millions of kilowatt hours of electricity.
Over the last few years, dairy farms across the country have been breaking down manure and converting the resulting methane into electricity. Systems called "dairy digesters" burn the methane—a powerful greenhouse gas—but as they do so, these generators also release nitrogen oxides (NOx), which contribute to ozone pollution.
This smog vs. climate change conundrum has put California dairy farmers who wish to cut their methane emissions via cow power in a regulatory tight spot.
As P.J. Huffstutter reports for the LA Times, while the state calls for increased renewable energy use and decreased greenhouse gas pollution, some local air quality districts are refusing to issue permits for dairy digesters. Their priority number one: reduce smog.
Despite being new systems, some of California's dairy digesters—about 16 in all—may require upgrades costing in the hundreds of thousands of dollars in order to meet current NOx standards.
Until then, these well-meaning farmers face some indigestion.