Methane Digester

Reducing CoW METHANE EMISSIONS with Innovation

Renewable energy is one of the focuses of the Straus Dairy Farm’s carbon neutral dairy farming model. At the dairy farm, the methane digester (also known as a biodigester) captures methane (a potent greenhouse gas) from the cows’ manure and transforms it into electricity. Operating since 2004, the methane digester provides enough renewable energy to power the entire dairy farm, charge Albert Straus’ electric car and other farm vehicles.

The digester has significantly reduced methane emissions by more than 700 metric tons of CO2e each year. This is the equivalent of eliminating annual greenhouse gas emissions from about 150 passenger cars.

Poop to Power — Cow Manure Methane Fuels the Straus Dairy Farm

In 2017, Albert Straus introduced the first full-scale electric truck – powered by cow manure. This innovation helped create a closed-loop on his dairy farm. This truck and the electric loader Albert introduced in 2022 are the on-farm electric vehicles demonstrating that his organic dairy farm can be carbon neutral, and livestock agriculture is one of the primary solutions to reversing climate change.

Dairy farmers in California are successfully lowering cow methane emissions under the state’s ambitious greenhouse gas reduction laws passed several years ago. The laws include manure methane emission reduction targets of 40% below 2013 levels by 2030. The state’s Air Resources Board suggests much of that reduction should come from converting methane from cow manure into energy.

“What I’ve tried to do is create a sustainable organic farming model that is good for the earth, the soil, the animals, and the people working on these farms, and helps revitalize rural communities."

First-of-its-Kind Collaboration: Straus Dairy Farm and BMW Group

The Straus Dairy Farm and BMW Group’s collaboration created a new farm-to-electric pathway in 2019 that ensured the Straus farm could invest in and test an advanced biodigester technology. With costs between $1 and $2 million, small-scale methane digesters have not been affordable for smaller dairies. This advanced technology is an upgraded version of the methane biodigester that has been operating on the Straus farm since 2004.

California’s Low Carbon Fuel Standard Program (LCFS) Success

Straus Dairy Farm’s methane digester generated approximately 250 megawatts of renewable electricity in 2021. This newly designed digester technology piloted on the farm will help make methane digesters more affordable for small-scale organic dairy farms. This will enable the reduction of methane emissions and create additional revenue sources for farmers through the sale of carbon credits under the LCFS program. Straus Family Creamery is helping the other California dairy farms in our supplier group install methane digesters within this decade.

A methane generator currently powers the Straus Dairy Farm and exports energy to the California power grid. In January 2021, the electricity began “powering” BMW electric vehicles. This collaboration creates two to four times more revenue than the standard utility agreement for the Straus farm.

"The exciting thing about dairy biodigesters is that they create a double-carbon emission reduction. On the one hand, they capture methane emissions from manure on farms that would otherwise be released into the atmosphere. And they also produce electricity which replaces fossil-fuel generation on the grid."

How the Methane Digester Works

Twice a day the barns are flushed clean with recycled water. Manure from the barn is also scraped by tractor into a holding pond. From there, the manure goes through a separator, which splits solids from liquids. The solids are then composted while the liquids are piped into a second pond covered with an enormous tarp. Under the tarp, the liquid manure is transformed by bacteria through the process of anaerobic digestion. The result of this sustainable practice is renewable energy in the form of methane gas, carbon dioxide, and a small amount of hydrogen sulfite.

The tarp captures the gas, which is pumped to a combustion engine where it fuels a generator and creates electricity. The heat created in the process provides 180° F water that is used to clean barns on the dairy farm.

Methane Digester’s Sustainable Benefits

There are many benefits to this system beyond the energy it generates. The most important is preventing methane gas from entering the atmosphere. Methane is a greenhouse gas and a short-term pollutant that is 86 times more detrimental than carbon dioxide within a 20-year period. The system also greatly eliminates odors on the farm and significantly reduces flies. In addition, two byproducts — separated solids and leftover liquids — are used as organic fertilizer on pastures. Plus, the system allows the Straus Dairy Farm to run electrical meters in reverse and to offset electrical usage from other meters at the farm.

The Sustainable Facts:

Generator capacity

71 kW

Annual Biogas Capture

1 M SCF

Average performance per day

600 kWh

Average performance per year

19994 kWh