Mooo-ving Towards Clean Energy

On a northern California farm, the cows are fueling innovation.

On a farm in Point Reyes, in northern California, cows are fueling their own dairy with their, uh…, manure. About half of the power at the Point Reyes Farmstead Cheese Company comes from a methane biodigester, which turns liquid manure into clean fuel.

In the last couple of years, methane biodigesters have become big business among large farms in California’s Central Valley. Government programs subsidize dairies who aim both to cut greenhouse gas emissions and to reap profits from selling carbon credits to big oil and gas companies. While these larger operations have their critics — some suspect that already crowded factory farms will expand just to exploit carbon credits, while others worry about ammonia byproducts — the Point Reyes farm installed its digester from a sustainability perspective.

Diana Giacomini Hagan, co-owner and CFO for the cheese company, talked to Bluedot Living about the purpose and challenges of installing a biodigester.


First, a little background. Robert Giacomini and his late wife, Dean, bought this beautiful piece of land in Marin County in 1959 and started a dairy farm. They raised four daughters, who all left the farm to pursue other careers before ultimately returning in the late 1990s — leading to the operation now being women-owned. This generation has shifted the dairy’s focus from milk to cheese. The creamery is known for its Original Blue, as well as many other cheeses. In addition to the farm, they operate a cheese manufacturing facility in nearby Petaluma.

“My father was always an innovator in the dairy industry,” Diana said, adding that he was also involved in dairy issues at the state and national level. “So he was tied into new innovations,” she said. In the mid-aughts, he started considering installing a methane digester. By 2010, the digester was up and running, making it Marin County’s second digester. (The first was at Straus Dairy.)

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How does it work? Solids are separated out for use as compost, and the leftover fibers can even become bedding for the cows. The liquid goes into a tarp-covered pond, where bacteria break down the organic waste into methane. “The methane gas is captured underneath that tarp,” Diana said, and then fed into a combustion engine that converts the gas into renewable energy, fueling about 40-50% of the farm’s current operation. Other examples of not wasting resources include: Excess liquid manure fertilizing fields where the farm grows silage for the cows; and heat exchange plates even capture warmth from the combustion engine, which is used for pasteurization, reducing the amount of propane needed.

Diana would like to fully fuel the farm with renewable energy, but there are roadblocks, including cost and bureaucracy. If the farm upsizes the digester’s engine to provide more power, they will have to pay prohibitively higher rates to PG&E for whatever extra power they’ll still need to purchase, she said. (In rural areas, where demands on the grid are relatively low, companies like PG&E may raise their rates in order to continue meeting income goals when “too much” green energy is being fed back into the grid and demand, consequently, is declining.) They applied for permits to add solar to the farm in 2022 and are still awaiting approval. 

Nor have all the digester parts lasted as long as expected. The farm is already on its third generator and engine. “It’s a little bit of a mixed bag,” Diana said. But it’s integral to the farm’s sustainability story. “It’s part of us wanting to do some things that maybe don’t make as much sense on paper but are the right thing for the environment.” 

Diana likes the elegant solution of fueling a dairy with the cows’ own waste. “There’s a lot of greenhouse gas emissions that come off of manure,” she said. “So having a system where you can convert those is a win-win. You’re creating another energy source, and you’re also reducing your carbon footprint while reducing electricity costs.”

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Teresa Bergen
Teresa Bergen
Teresa Bergen is a Portland, Oregon-based author who specializes in the outdoors, vegan and sustainable travel. Her articles appear in many publications and she’s author of Easy Portland Outdoors and co-author of Historic Cemeteries of Portland, Oregon.
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