California laws becoming 'dairy digester' intolerant

Summary:Dairy farmers in California are trying to reduce greenhouse gas emissions by converting methane-rich cow manure to electricity. The problem? The process causes air pollution.

Three years ago, I encountered the worst smell of my life: cow waste.

Never had I been so close to so much methane and ammonia gas, or so many of its bovine emitters. I was visiting Vermont's Blue Spruce Farm during a Society of Environmental Journalists meeting.

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.


This post was originally published on

Topics: Innovation


Contributing Editor Melissa Mahony has written for Scientific American Mind, Audubon Magazine, Plenty Magazine and LiveScience. Formerly, she was an editor at Wildlife Conservation magazine. She holds degrees from Boston College and New York University's Science, Health, and Environmental Reporting Program. She is based in New York.... Full Bio

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