Two NorCal Dairies Use Methane Digesters to Help Reduce Electricity & Fuel Costs

Written By: By Gary Quackenbush
Published: April 3, 2019

Authors’s Note: Methane from farm animals is included among greenhouse gases that must be reduced to protect the environment. In this issue, we feature the first of a two-part series focusing on the use of methane digesters, followed by a second article in May about research at UC Davis designed to help offset methane production through feed modification and other sustainable practices.

Removing methane from the atmosphere can also save money on energy with the potential for making a contribution to farm revenue if biogas is sold to power companies and natural gas distributors.

Albert Straus, owner of Straus Family Creamery, is a leader in sustainable organic dairy farming and a proponent of carbon farming to improve soil health as a climate change solution. He practices organic grassland management and maximizes pasture growth to reduce off-farm feed imports.

Beginning in 2013, two of his carbon-farmed pastures that use commercial compost, pasture numbers 3 and 4, saw a major increase in dry weight grass per acre going from 5,100 lbs. to 6,391 lbs., which exceeded even the best growth years without carbon farming, going back two decades. This upward trend continues today.

“In 2013, Straus Dairy Farm became the first dairy to implement a 20-year carbon farming plan in California, in conjunction with the Marin Carbon Project,” Straus said. “Methane is definitely a problem. In 2004 we installed an anaerobic digester at a cost of about $350,000, which we paid off in four or five years. Since we have cows on pasture most of the year at our 280-cow dairy farm, we only get about 60 percent of the manure for the methane digester from feeding areas and milking barns.”

He is working with a company (under a nondisclosure agreement) to build and operate small-scale digesters on farms to implement as a pilot project. The aim is to reduce digester cost to about $400/cow, plus a generator that could range from $60,000 to $100,000. Also in the works is a plan to obtain alternative fuel credits at a higher rate than through the cap and trade process — with more details coming soon.

Straus said U.S. farms operate on the edge. While there were 4.6 million dairy farms in 1940, now, the number is under 40,000, a figure that he said could fall under 20,000 in the next decade. In 1940, there were approximately 22 million dairy cows. In 2016, the number was down to 9 million.

He defines carbon farming on organic dairy farms as a process that helps move carbon from the atmosphere and back into the soil. Elements of this practice involve intensive rotational grazing enabled by mobile pasture fencing that allows grassland to regrow and utilize more CO2 through photosynthesis. Hedgerows are also planted adjacent to perimeter fences to serve as windbreaks and to protect the soil against rain erosion. In addition, he said he believes in on-farm composting to increase soil organic matter by providing essential nutrients back to the earth.

According to the Marin Carbon Project, adopting these practices can bring huge benefits. If farmers spread a quarter inch of compost on just 50 percent of California’s rangelands, 42 million metric tons of CO2e would be offset, which is equivalent to all the energy use for commercial and residential sectors in the state.

Straus uses biogas from a methane digester to produce a renewable energy source to power the entire dairy farm and the electric farm vehicles.

In general, the cost of commercial microbial anaerobic digesters can range from $400,000 to $5,000,000 depending upon the size of the operation and technology used. The typical on-farm anaerobic digestion unit costs approximately $1.2 million. Costs vary, depending upon the size of the unit, design, and features. Some simple, small scale and portable backyard systems cost under $200 up to several thousand dollars.

At the Point Reyes Dairy and the Point Reyes Farmstead Cheese Company, owned and operated by Robert Giacomini’s daughters, a digester was installed in 2010 that produces power to supply 65 percent of the dairy and creamery’s energy needs.

“We’re currently in our second technology stage with a new engine installed two years ago. The cost is high, but state grants have been available,” said Jill Giacomini Basch.

Her sister, Diana Giacomini Hagan, said converting methane to energy is part of their company’s sustainability model. They use a rapid flow separator system to remove dry solids from manure for composting on the farm, to provide bedding for cows and fertilizer for pastures. Liquid waste is transferred to a holding pond where CH4 is captured and sent to power a generator.

“We are saving on propane costs that once went to heat water as well as offsetting electric charges for a portion of cheese production,” Haygan said. “The size of the dairy determines how much up-front money may be available, but costs have been coming down a lot on a cost-per-cow basis – with most of the cost associated with the generator.”

Daryl Maas, a principal with Mass Energy Works in Redding, CA., assists dairy farmers in California, Oregon, and Washington in addressing their methane reduction needs. He said his firm serves about two-thirds of the demand for recent digestor construction.

“A lot more people are coming into this market. Digestors are an ideal environmental mitigation tool that pays for itself and enhances what dairies are doing to reduce GHGs,” Maas said. “There were a lot of skeptics at first, but when people see the benefits as well as the opportunity to make money, they realize that good returns are possible by selling biogas into the power grid.”

He also said that to sell into the natural gas market, methane has to be cleaned by a special processor that can cost about $5 million. To offset this cost, several dairies are forming cluster groups, or coops, to combine financial resources and make the investment – including multiple dairies in Tulare and Merced Counties in the central valley where farms and dairy herds are larger making such investments pencil out. In Northern California, digesters are used by two farms in the Sacramento area as well as two in Sonoma County.

Grants are available from the California Department of Food and Agriculture for digesters and to help farmers access the natural gas pipeline, but not for the power grid, since the state does not want to encourage the production of more GHGs, Maas said.

In 2019, $61 to $75 million in CDFA grants are available through a competitive grant solicitation process. Go to for details. In brief, this program can provide
project grant amounts up to $3 million with a 50 percent match required for a commercial California dairy site. The maximum project duration is from October 1, 2019, to September 30, 2021. Grant applications were due by 5:00 p.m. PDT on April 3, 2019. The review period is from May to August 2019, award funding will be announced in September 2019. Other CARB and DDRDP requirements also apply. A Financial Assistance Application Submittal Tool (FAAST) is available at

“Since 2005, new regulations for holding ponds have required plastic liners, upping construction costs,” Maas said. “Our goal as consultants is to help our clients realize that this technology is more reliable, simple and user-friendly today than ever before. We are also managing systems as well as owning, building and operating others designed to convert bio-methane to renewable electricity or fuel.”

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