Some Stanislaus and Merced County dairies will now convert cow manure to truck fuel

A company’s plan to expand its biogas pipeline to 60 miles in Stanislaus and Merced counties passed a county environmental review and will connect 21 additional dairies.

In late November, the Stanislaus County Board of Supervisors found there was no substantial evidence the 24 miles of additional pipeline will have detrimental effects on the environment in terms of aesthetics, land use and planning, public services, greenhouse gas emissions and water quality.

County leaders decided the pipeline expansion did not require a full-blown environmental impact report. A study done on the original Aemetis project in October 2020 said the Keyes biogas cleanup plant — where methane pumped from dairies is stripped of carbon dioxide — produces some emissions but those are outweighed by a net reduction of emissions from traditional dairy operations.

The Aemetis Inc. pipeline carries methane gas from dairy digesters to the company’s biofuels facility in Keyes, where the company also has an ethanol plant.

The project currently includes 36 miles of underground pipe, seven dairies with digesters breaking down manure and 10 dairies with digesters under construction. The methane gas captured at dairies is sent to the Aemetis facility in Keyes, where carbon dioxide is removed to produce clean natural gas.

The Keyes facility has an interconnection with Pacific Gas & Electric Co. for sending the renewable natural gas to transportation fuel stations around the state. Aemetis, based in Cupertino, also is building a station at Keyes for dispensing the fuel derived from cow manure to heavy trucks, starting next year.

A company official said the Aemetis project is improving air quality in the region by capturing methane emissions at dairies and providing an alternative to air-polluting diesel fuel.

Dairies, livestock major source of methane emissions

It’s also a method for reducing greenhouse emissions that are warming the planet. Methane is responsible for an estimated 25% of global warming. More than half the methane emissions in California come from dairies and livestock, according to the state Air Resources Board.

“The capture of methane at dairies and conversion into below zero carbon intensity renewable fuel to replace diesel for heavy trucks provides immediate benefits ... and provides a lower cost renewable fuel for heavy trucking,” Aemetis Chairman and CEO Eric McAfee said in a company news release.

Use of renewable natural gas represents a 90% reduction in emissions when compared to petroleum diesel fuel, the company said. In the first half of October, the average retail price of diesel fuel was $4.52 per gallon nationwide, compared to the energy equivalent of $2.85 for natural gas.

Rob Macias, the company’s vice president of biogas, said there’s a one-to-one ratio of cows to vehicles powered by renewable natural gas. He said the project is getting renewable natural gas from the poop of 16,000 cows, and that’s enough energy for running 16,000 passenger vehicles for a year.

When the expansion is completed, the Stanislaus-Merced biogas project will collect methane from 38 dairies. It is shooting to reduce emissions equal to 6.8 million metric tons of carbon dioxide over 10 years, which is equivalent to eliminating tailpipe emissions of 150,000 cars each year.

Incentives help Stanislaus farmers meet the goal for cleaning Central Valley air

Stanislaus County officials, in approving the environmental review, recognized the Aemetis project will improve regional air quality by reducing methane, carbon dioxide, nitrous oxide and hydrogen sulfide emissions associated with dairies.

A spokesperson for San Joaquin Valley Air Pollution Control said Monday the district has no data on emission reductions achieved by the Aemetis project thus far. According to the spokesperson, the air district doesn’t regulate methane emissions from dairy farms, but the California Air Resources Board is responsible for determining the methane gas reductions achieved by dairy digester projects.

The state air board released numbers showing an annual reduction of 87,146 metric tons of carbon dioxide equivalent from eight fully or partly operational dairy digesters in the Aemetis project. The reductions for individual digesters ranged from 8,086 to 18,985 tons.

Some scholars have criticized the air board’s method of measuring dairy industry methane emissions, saying it’s based on herd surveys and estimates, not on emissions data.

Expanded pipeline to take in more dairies

Macias said the pipeline extends west and south from the Keyes facility to connect dairies west of Turlock and south along Central Avenue to the Hilmar area. The additional 24 miles of underground pipe will be fingers coming off the existing line to take in more dairies, he said.

Aemetis has worked in coordination with county Public Works to install the 8-inch-diameter pipeline in the right-of-way of county roads.

Macias said the digesters are capturing the methane and hydrogen sulfide emissions that are byproducts of fermentation in dairy manure lagoons, thereby reducing the odors of dairy farms.

The project provides nominal payments to participating dairies, but the owners won’t get rich from it, Macias said.

Support from grant funding

Aemetis says it has received $57 million in grant funding and other government agency support for the biogas dairy project, upgrades to the Keyes biofuels facility and a proposed sustainable aviation fuel project at the former Army ammunition plant in Riverbank. The support has come from the California Air Resources Board, the U.S. Department of Agriculture, the U.S. Forest Service, California Energy Commission and PG&E’s energy efficiency program.

The California Air Resources Board is considering the future of incentives for companies that convert cow manure to biofuels under the state’s Low Carbon Fuel Standard, according to a CalMatters article. Utilities like PG&E are required to pay for biofuels as the state tries to battle climate change.

There are around 130 state-funded dairy digester projects in California. In a progress report last year, the Air Resources Board said the dairy industry in this decade could achieve methane emission reductions equivalent to 4.6 million metric tons of carbon dioxide mostly through digester projects. It’s about halfway to the 2030 methane emission target set for the dairy and livestock sector in Senate Bill 1383.

Scientific studies in Wisconsin, Washington state and other countries have raised some concerns about manure digesters increasing ammonia emissions around dairies.

The Leadership Counsel for Justice & Accountability, which has offices in Merced and Fresno, has expressed concerns that projects to convert manure to natural gas fuels will encourage larger dairies, with a greater concentration of cows and wastes, serving to intensify ammonia emissions and water contamination.

The group didn’t have a comment on the Stanislaus-Merced project.

Stanislaus County Supervisor Vito Chiesa, whose district includes the pipeline, said grant funding for the biogas endeavor is a good investment. “We are going to see air quality benefits for the Valley because of this,” Chiesa said. “Dairies are under so much pressure as it is. This is a great private-public partnership that will be beneficial for the valley and the air we breathe.”

Chiesa said there are other dairy farm clusters in the San Joaquin Valley where biogas projects could cut back on methane emissions.