By Raleigh Gerber on

by Todd Campbell, Vice President Public Policy and Regulatory Affairs, Clean Energy

Natural gas is the leading alternative to diesel in medium- and heavy-duty vehicles in California. Over 200 million gasoline equivalent gallons (GGE) of natural gas are consumed every year by buses and trucks in California. Much of that is used here in the South Coast Air Basin—an important region for California’s booming goods movement sector that is also plagued with the nation’s worst air quality—the result of an increasing number of on-road diesel trucks transporting goods from busy ports to warehouses inland.
What many may not realize is that about 150 million GGE, nearly 75%, of the methane used as a transportation fuel in California comes from renewable sources. Until recently, most of the renewable natural gas (RNG) consumed by California NGVs came from out-of-state sources, mainly from landfills. This is rapidly changing, however, with sophisticated and increasingly largescale projects now injecting methane from California dairy digesters directly into the state’s natural gas pipeline.

Dairy Digesters Expand in California

In early January, Calgren, a California bioenergy company, began injecting biomethane from four new dairy digester projects into SoCalGas’ existing grid near the company’s headquarters in Pixley, California. These new digesters have more recently been joined by six additional dairy manure biogas production facilities, all supplying California vehicles with locally produced biogas. Calgren has been producing other renewable vehicle fuels in the area since 2008 and has used biogas as a part of its ethanol production process since 2013. The six newest dairies more than double the biomethane output of the Pixley cluster—the largest in the nation. Altogether, the ten dairies collect gas from more than 66,000 cows, or roughly 6.5 million DGE per year.

A Plentiful, Carbon-Negative Fuel

Capturing methane from cow manure is critical to the state’s strategy to reduce short lived climate pollutants (SLCPs), including fugitive methane, and even more essential to reducing vulnerable populations’ exposure to deadly diesel exhaust. When dairy RNG is used in the latest generation of near-zero emission natural gas trucks, not only are the NOx emissions lower than those from comparably sized electric trucks charged by the California grid, but the GHG emissions are about 330% lower as well. That’s because dairy biogas has a negative carbon footprint—burning dairy biogas in an NGV actually removes carbon from the atmosphere, which is why it’s referred to as a “carbon negative fuel”.

A Wave of New RNG Projects in California

Calgren was the first dairy digester developer to inject dairy biogas into the California natural gas system starting in 2019, representing only the first wave of dairy biomethane that is expected to come online in the next three to four years. The California Department of Food and Agriculture (CDFA) has awarded grants totaling $183.3 million between FY 15 and FY 19, funding 107 dairy biogas projects currently in development in California. The 2020 Dairy Digester Research and Development Program (DDRDP) budget has allocated $34 million to fund more dairy RNG projects in 2020. Studies are currently underway to calculate the total biomethane production of the CDFA-funded projects, but assuming an average of 3,000 cows per dairy, all of the currently funded DDRDP projects will produce over 35 million DGE of RNG annually—nearly a quarter of the amount of natural gas consumed in California by the transportation industry. According to Lyle Schlyer, Calgren’s CEO, “Using RNG to power California freight vehicles makes sense—it is the only technology currently available for that purpose. Fueling those vehicles with methane that would otherwise have been released into the California environment is clearly a home run.”

A Critical Component of California’s Clean Energy Portfolio

Dairy digester projects are by far the most cost-effective way to reduce GHG emissions. Study after study arrives at the same conclusion—California’s greenhouse gas reduction funds are best spent investing in projects that divert dairy manure to in-state digester projects, which produce a carbon-negative transportation fuel in return. When the RNG produced from capturing and processing methane is used in ultra-low-NOx trucks, it is among the most cost-effective ways to reduce diesel exhaust. Investing more—not less—money in rapidly converting all of California’s 1,300 dairies to modern, RNG-producing facilities while making more—not less—funding available to replace thousands of dirty diesel vehicles with ultra-clean medium and heavy-duty natural gas trucks fueled with in-state RNG is a critical strategy to capturing harmful emissions while fueling the state’s transportation industry with a plentiful, cost-effective, renewable fuel.