New biogas plant in Marin County turns local trash into energy

The new biogas plant at the Redwood Landfill in Novato began operating in September 2017. (Cynthia Sweeney / North Bay Business Journal)


The next time you flip on a light switch, you might think about that trash you took out last week.

A Novato biogas plant is taking locally collected garbage and turning it into electricity for local consumption. Biogas is a renewable fuel, primarily a mixture of methane and carbon, and producing it is much more efficient than solar power. It would take between 64–84 acres of solar arrays to produce the 3.9 megawatts of power the biogas plant is capable of, said Karen Stern, communications manager, Waste Management, Northern California.

The plant, which began service in September, was built by Waste Management, a nationwide company based in Houston. It owns and manages the landfill.

MCE, formerly known as Marin Clean Energy, has entered into a 20-year agreement with Waste Management to purchase the electricity.

The plant is estimated to provide enough renewable electricity to serve more than 5,000 MCE customers in Marin and Napa counties and the cities of Benicia, El Cerrito, Lafayette, Richmond, San Pablo and Walnut Creek.

How the biogas plant works: The organic trash, like food and paper, is collected from homes and businesses and buried. As it decomposes, it begins to emit gas, which is captured by a network of 106 wells scattered around the landfill. The gas is contained, carbon filters capture the moisture, and a treatment system of compressors cool and filter the gas to remove toxic particles.

The processed gas is then piped to two reciprocating engines that turn a generator that creates electricity. The electricity is then exported to MCE customers.

Exhaust from the engines is also treated to remove carbon monoxide and nitrogen oxide making it one of the lowest emission facilities of its kind, said Ramin Khany, district manager of the Redwood Landfill and Recycling Center.

Collecting the gas emitted from a landfill isn’t new. But what’s unique about the Redwood plant is that the methane gas generated by the decomposition of organic materials in the landfill will power the plant. Previously, 100 percent of the collected gas was flared off.

Waste Management estimates the plant will eliminate 8,900 metric tons of greenhouse gas emissions each year.

Waste Management has about 80 biogas plants around the U.S., the next closest one to the Novato plant is located in Livermore.

At $14.5 million, this facility is expensive compared to other biogas plants the company has built, due to having to meet stricter environmental regulations in California, Khany said. Elsewhere, the plants have cost about $11 million to build.

“The margin of profit is not high, but the good its doing is deeply satisfying for the company,” he said.

Biogas is in a good position to overtake solar power as a source of energy, said Patrick Serfass, executive director at the American Biogas Council.

“The growth potential for renewable natural gas is outpacing solar. Factors behind the potential include 66.5 million tons of food waste in the U.S. each year, manure from 8 trillion cows, chickens, turkeys and pigs, and the petroleum industry’s fracking surge has unleashed abundant, low-cost natural gas,” he told Capitol politicians earlier this year.

Waste Management would like to build more plants like the Redwood facility, but sites need to meet certain criteria. The Novato site fit the profile as it’s close to a power source (PG&E) close to city infrastructure, and a distribution partner like MCE.

MCE, is a clean-energy supplier that also has an agreement with PG&E to purchase electricity from alternative power sources like solar, wind, geothermal and hydropower, and feed it through PG&E’s wires to customers. PG&E also remains responsible for billing and maintenance to the system.

Customers can opt out of the service and sign with PG&E directly, but MCE serves 83 percent of the population it covers.

Waste Management has been using landfill to gas to electricity technology since the 1980’s. Previously, materials like wood was also burned to create electricity, Khany said. As environmental regulations have increased and with technological advances, energy creation and use has gotten more efficient.

In addition to the power plant, Redwood Landfill produces about 500 tons a day of a natural fertilizer that is used for organic farming, including vineyards.

The landfill also recycles almost half of all materials brought to the facility, and it donated 180 acres of its property to the Marin Audubon Society for wetlands restoration.

At 222 acres, the landfill is expected to reach capacity in 2030, and will be expanded or converted to a transfer station.

The landfill takes in 800 tons of trash a day, and the goal, Khany said, is to divert 90 percent of the trash in 40 years. Waste Management is currently designing and developing an automated sorter in Oakland. Using optical sorters and air vents, it can basically take a bag full of trash and sort all the organic material out.

“It was something very impressive. The technology is not there yet, but we’re getting there,” he said.

Cynthia Sweeney covers health care, hospitality, residential real estate, education, employment and business insurance. Reach her at or call 707-521-4259.