Bioenergy · Analysis

Puente Hills still makes power from buried trash, for now

A closed landfill above the 60 Freeway keeps spinning generators on its own methane. The supply falls every year, and you can watch it decline in the public record.

BY THE RENEWABLE ENERGY LA EDITORS · FILED OCTOBER 27, 2026 · 6 MIN READ ·

How buried trash becomes a kilowatt

Organic waste (food scraps, yard clippings, paper) breaks down without air deep inside a capped landfill, and that decomposition gives off landfill gas, a roughly half-and-half mix of methane and carbon dioxide. A grid of wells drilled into the waste, connected by pipes (the gas collection and control system), pulls that gas out under slight vacuum so it does not just leak to the sky.

That collected gas feeds engines that spin generators. At last public report the Puente Hills gas-to-energy plant was rated on the order of 50 megawatts, enough to cover tens of thousands of homes when the gas is flowing well, though real output runs lower and drifts down year over year. Gas the plant cannot use gets burned off in a flare, which is worse for the climate than capturing it but far better than venting raw methane, a greenhouse gas many times stronger than carbon dioxide over its first couple of decades.

The math of a renewable that is running out

Once a landfill stops taking waste, gas production peaks and then falls along a long, slow decay curve. Puente Hills stopped accepting trash in 2013, so it is well past its peak, and each year the collection system pulls a little less. Nobody can give you the exact date the plant goes dark, because it depends on how the buried waste keeps decomposing and on what the economics look like once output gets low.

Set against basin demand this is a small resource. LA County can draw well over ten thousand megawatts on a hot afternoon, and a declining landfill plant is close to a rounding error next to the desert solar and battery projects feeding the region. Its value is different: it runs day and night regardless of sun or wind, and it destroys methane that would otherwise escape, which is the part worth protecting even as the electricity fades.

Who runs it, and what you can check

The site has several names on it. The Sanitation Districts of Los Angeles County own and operate both the closed landfill and the power plant. CalRecycle, the state recycling and waste agency, tracks the landfill in its public facility database. The California Air Resources Board's landfill methane rule sets how much gas the site has to capture, and the South Coast air district permits the engines and flares that burn it.

For the plant itself, the Sanitation Districts' own pages are the first stop, with status and output figures you can compare from one year to the next. The federal Landfill Methane Outreach Program keeps a project record you can cross-check, and the state waste database confirms the landfill's closed status and basic facts. Read two or three of these together and you get an honest picture rather than a single agency's framing.

Worth watching this month

1. The Sanitation Districts' next public reporting on Puente Hills energy output, which should show whether the yearly decline is steady or steepening (this one actually matters).

2. Any South Coast Air Quality Management District permit action on the site's engines or flares, routine paperwork most years but worth a glance.

3. California Air Resources Board updates to the landfill methane regulation, which could change how much gas the closed site must keep capturing even after the generators stop.

4. CalRecycle's facility record for Puente Hills, where a status change would be the clearest early signal the plant is winding down.

5. Any Sanitation Districts board agenda item touching the gas-to-energy plant's future, usually routine, occasionally the real news.

Where this dispatch reads

Sanitation Districts of Los Angeles County (operator), www.lacsd.org, The public agency that runs the landfill and the gas-to-energy plant; look here for plant status and year-over-year output figures.
CalRecycle Solid Waste Information System (state .gov), www2.calrecycle.ca.gov/SWFacilities/Directory, State waste agency's facility directory; confirms Puente Hills' closed status and basic site facts.
US EPA Landfill Methane Outreach Program (federal .gov), www.epa.gov/lmop, Federal program with a project database for landfill gas energy projects you can cross-check against the operator's numbers.
California Air Resources Board, landfill methane regulation (state .gov), ww2.arb.ca.gov/our-work/programs/landfill-methane-regulation, The state rule setting how much gas a landfill must capture, which outlasts the power plant itself.
US Energy Information Administration, landfill gas explainer (federal .gov), www.eia.gov/energyexplained/biomass/landfill-gas-and-biogas.php, Plain federal explainer on how landfill gas is formed and used for electricity.
California Independent System Operator (grid operator), www.caiso.com, The grid operator for most of California; context for where small resources like this land on the system.

Questions readers have asked

Is landfill gas really renewable?

It counts as renewable under California rules because the buried waste keeps producing gas on its own. But a closed landfill's supply only falls over time, so it is a renewable that is running out rather than one that refills.

Does this power my house?

The plant sits in Southern California Edison territory, not LADWP's. If you are an LADWP customer inside the city of LA it is probably not on your meter, though it still helps supply the wider basin.

What happens when the gas runs too low?

The generators get shut down when output no longer pays. The site will likely still collect and flare gas for years after that, because the methane-capture rules outlast the power plant.

Why flare gas instead of using all of it?

Flaring handles gas the engines cannot take, or burns it off when they are down for maintenance. Turning methane into carbon dioxide this way is far less harmful than letting raw methane escape, even though capturing it for power is better still.