Excerpt from this story from Sierra Club:

Livestock operations have been harvesting methane for over 20 years, but until recently, the gas was used mostly to generate heat and electricity for the farms themselves. Now, state and federal incentives are prompting a rapid build-out of digesters across the country so they can generate “renewable natural gas.” According to the US EPA, 290 dairy digesters were online as of January 2023. Though these operations are promoted as a climate change solution, they hog enormous volumes of water and create noise, odors, dust, and air and water pollution in the communities that host them. They’re also feeding consolidation, making it harder for smaller dairies, including those with truly sustainable practices, to survive.

As reported in High Country News, mega-dairies in Arizona are sucking up so much groundwater that residential wells are going dry, and in Minnesota, huge operations are driving small dairies out of business. In the dairy capital of Wisconsin, where mega-dairies have rapidly displaced smaller operations, nitrates and E. coli have contaminated drinking water wells. Just last month, a Wisconsin court ruled against dairy industry interests in a suit that would have undermined a state water protection program that regulates animal waste.

California’s Low Carbon Fuel Standard (LCFS) is driving the manure gold rush. Though it’s a state program, any producer that sells transportation fuel in California can participate. The state assigns every transportation fuel a carbon intensity score, which is a measure of the greenhouse gas emissions created per unit of fuel. High-carbon fossil fuels earn scores close to 100; solar-powered electricity has a score of zero. Every producer must stay below the state’s carbon-intensity target, which gets lower every year. To meet the threshold, producers of high-carbon fuels can buy credits for low-carbon fuels on the open market. 

Biogas products from dairy digesters typically earn negative scores, some as low as -790. Producers are allowed to account for the emissions avoided by capturing the methane—a potent greenhouse gas—instead of releasing it into the atmosphere. “Because of that extreme negative carbon intensity, it creates this perverse incentive structure that makes it the most lucrative fuel on the market,” says Lobdell. These operations do nothing to address methane released through enteric fermentation—i.e., the gas released when cows burp—and a new analysis by Food & Water Watch shows that digesters leak substantial amounts of methane.

Nevertheless, California has turned to dairy biogas to help meet its ambitious carbon-reduction targets. The state’s Department of Agriculture offers grants that cover up to half of the (substantial) cost of building out digesters. Once they’re up and running, operations can sell credits through California’s LCFS market and the federal Renewable Fuel Standard program simultaneously. The California Department of Food and Agriculture has funded 140 anaerobic digester projects within the state, and a new report from the Center for Food Safety shows that the cost to taxpayers is much higher than state regulators claim.