Key Takeaways
California pays dairy farmers to capture the methane from cattle manure and turn it into natural gas, rewarding them with Low Carbon Fuel Standard credits that oil companies buy.
A growing body of research says the program's carbon math overstates the climate benefit by treating short-lived methane and long-lived carbon dioxide as if they cancel out.
California extended parts of the program past 2050 in 2024, and a new air board proposal could send millions more dollars to dairies.
California's marquee climate program has a manure problem.
For years the state has paid dairy farmers, in California and beyond, to capture the methane that rises off manure lagoons and turn it into natural gas. Farmers who install anaerobic digesters earn Low Carbon Fuel Standard credits, which oil companies buy to meet the state's requirement to lower the carbon in their fuels. The subsidies are lucrative, and the program has grown fast.
The trouble is the accounting, according to a MIT Technology Review analysis of a growing body of research. California treats methane as though it warms the planet about 25 times as much as carbon dioxide over 100 years. Methane is far more powerful in the near term, but it breaks down within a couple of decades, while carbon dioxide keeps heating the atmosphere for centuries. A system that credits capturing methane today, while permitting more carbon dioxide in its place, can trade a short-term win for near-permanent warming.
The scale of a single credit is striking. One biogas-powered vehicle can generate enough credits to offset the deficits of 26 gasoline vehicles, according to University of California, Berkeley economist Aaron Smith. Peer-reviewed work on dairy biomethane has reached a similar conclusion, warning that offset crediting in fuel standards can overstate real emissions cuts.
Cutting methane is still worth doing, and digesters do it. The point researchers press is that the climate needs deep cuts in both gases, not a paper swap of one for the other.
The stakes are rising. California moved in 2024 to extend parts of the program past 2050, and the state's air resources board has floated a plan that could send millions more dollars to dairies while easing limits on big emitters. This is the same food-system accountability question WYDE keeps running into, from the egg price-fixing settlement to the SNAP cost shift now landing on states. Worth watching.
People Also Ask
What are California's dairy digester credits?
They are Low Carbon Fuel Standard credits that California awards to dairies that capture methane from manure and turn it into natural gas. Fuel companies buy the credits to meet the state's carbon rules.
Why do researchers say the carbon math is flawed?
Because the program treats short-lived methane and long-lived carbon dioxide as if they offset each other. Methane fades within decades, while carbon dioxide warms the atmosphere for centuries, so the swap can lock in more long-term warming.
Do methane digesters still help the climate?
Cutting methane is worth doing, and digesters do capture it. Researchers argue the climate needs deep cuts in both methane and carbon dioxide, not a credit that trades one for the other.
Is California expanding the program?
Yes. The state moved in 2024 to extend parts of the program past 2050, and its air resources board has proposed a plan that could direct millions more dollars to dairies.