Clean Energy SF: San Francisco, fog then sun, est. 2026

Vol. 1 - No. 14 - Thursday, September 24, 2026 - Free to readers

Bioenergy ยท Analysis

Altamont's methane: how the Bay Area's trash heap feeds the grid and the fuel pump

The Bay Area's garbage rots into methane east of the hills at the Altamont Landfill. Some of it runs engines for the grid, and some is cleaned into vehicle fuel under rules you can look up.

Filed November 2, 2026 By the Clean Energy SF editors Reading time: 6 minutes

I. How a buried mountain makes electricity

Set your black bin on a San Francisco curb on collection day and the trash inside starts a long trip east. Recology, the city's hauler, moves most of the city's household garbage out of San Francisco, over the hills, and toward the Altamont Landfill in eastern Alameda County, out past Livermore where the wind turbines turn. What you throw away does not simply vanish. It piles up, gets covered, and begins to rot.

Rotting garbage, sealed under soil without much oxygen, gives off methane, the same gas that heats most homes in the city. A landfill the size of Altamont produces a steady stream of it for decades, so a modern site is drilled through with a web of wells, perforated pipes sunk into the waste that pull the gas out under slight vacuum. The simplest use for what comes up is a set of large reciprocating engines, basically industrial versions of a car engine, that burn the gas to spin generators and feed electricity onto the local grid. Altamont has run gas-to-electricity equipment for many years, on the order of a few megawatts to low tens of megawatts at various points, per the operator's public descriptions, which is enough for a few thousand homes rather than a city.

II. From the grid to the fuel tank

Electricity is only part of what Altamont does with its gas. For years, the site has also housed a plant that takes a slice of the captured methane and cleans it far more thoroughly, stripping out the carbon dioxide and trace contaminants until what remains is nearly pure methane. Chilled until it turns liquid, that becomes liquefied natural gas, a transportation fuel. Waste Management, the landfill's operator, built the facility as one of the larger landfill-gas-to-LNG projects in the country when it opened, by the company's account.

What makes it tidy is the loop. The same trucks that haul garbage to the landfill can run on fuel made from that garbage, so a collection route can, in principle, power itself off what it collects. How much of the region's fleet actually runs on Altamont fuel, and whether the fuel plant is running flat out in any given year, shifts with contracts and economics, so treat any clean round number you hear with caution.

III. Where the rules live, and how to check them

The reason a landfill bothers to turn gas into vehicle fuel rather than just flaring it comes down to credits. California's Low Carbon Fuel Standard (the state program that rewards fuels with a lower carbon score and penalizes dirtier ones) assigns each fuel a certified pathway, and landfill gas tends to score well. The Air Resources Board publishes those pathways, so you can look up whether a given project has an approved pathway and roughly what score it earned.

Capture itself is not voluntary here. State rules require large California landfills to collect and control their gas, and operators report to both state agencies and the federal Environmental Protection Agency. This is the municipal cousin of the digester gas made at the city's wastewater plants, bigger and dirtier to clean, but governed by a paper trail that is just as public. CalRecycle tracks the facility, the Air Resources Board tracks the fuel, and the EPA's landfill program lists the project. None of it is a quick read, but it is all checkable.

IV. Worth watching this month

1. Watch the Air Resources Board's Low Carbon Fuel Standard pathway lookup for any updated or amended Altamont landfill-gas pathway, a routine filing that nonetheless signals whether the fuel operation is active.

2. Check CalRecycle's facility record for the Altamont Landfill for permit or capacity updates, usually routine but occasionally important for how long the site keeps taking waste.

3. Watch for Recology and City of San Francisco contract news about where the city's trash is hauled, which has been contested before and directly affects what feeds Altamont.

4. Keep an eye on the EPA's Landfill Methane Outreach Program project list for changes to Altamont's reported capture or energy projects.

5. Note any Bay Area Air Quality Management District action on landfill gas or flaring rules, most of which are routine but can tighten capture requirements.

Frequently asked questions

Does my San Francisco trash really end up at Altamont?

Most of the city's landfilled household waste has gone to the Altamont Landfill in eastern Alameda County, hauled by Recology. Exact destinations can shift with contracts, so it is worth checking current city and Recology notices.

Is landfill gas the same as the natural gas in my stove?

The main ingredient, methane, is the same molecule. Raw landfill gas is only about half methane and full of contaminants, so it has to be cleaned before it can match pipeline or vehicle-grade fuel.

Is burning landfill gas actually good for the climate?

Methane traps far more heat than the carbon dioxide you get from burning it, so capturing and burning it is generally better than letting it leak. It is a cleanup of unavoidable waste, not a clean primary energy source.

How is this different from the city's sewage gas?

Both make methane from decomposing waste, but sewage digesters handle a smaller, wetter, more controlled stream at wastewater plants, while a landfill works on a far larger and messier pile. The capture and cleaning challenges differ, so the two are cousins rather than twins.

References