California-based Windfall Bio—a startup with tech to convert waste methane from farms and landfill sites into organic fertilizer—is auctioning off substantial lab and bioreactor assets at its San Mateo headquarters and Texas demo-plant.
Silicon Valley Disposition lists a Windfall Bio online auction at the company’s San Mateo address, featuring “extremely high-end R&D instruments, bioreactor systems, lab equipment, and much more,” with assets including LC/MS/MS, GC/MS, HPLC systems, a freeze dryer, freezers, incubator shakers, and bench-top bioreactors.
A second auction in Humble, Texas, lists “large scale state-of-the-art bioreactor and related support equipment.”
The firm, which has raised $37 million ($9 million seed round in 2023, $28 million Series A in 2024) from backers including Prelude Ventures and Amazon’s Climate Pledge Fund, was founded in 2022 by Josh Silverman, Carla Risso, Ph.D, and Louis Stenmark.
It began construction of the demo plant last fall to showcase its technology using multiple waste gas sources, and said it was actively raising a Series B round.
According to the Department of Energy, Windfall was selected for a substantial grant in Dec 2024 to deploy methane bioconversion as a flare replacement system. However, the project subsequently appeared on a list of 321 terminated awards obtained by Latitude Media in October 2025.
Windfall Bio has not responded to requests for comment.
‘Everyone would like to make money from waste methane’
Speaking to AgFunderNews in November 2025, Silverman explained that waste methane produced by manure lagoons, waste management sites or landfills is typically released directly into the atmosphere, flared off, or turned into renewable natural gas (RNG) or electricity.
While the latter options were popular a few years ago, the economics are now far less favorable, he claimed. “So we said, can we do something better with the methane than just releasing it or burning it?”
Windfall’s microbes transform methane into nitrogen-rich biomass that can be processed into high-value organic fertilizer and directly used on a dairy farm or sold in the market.
According to Silverman, the system was easy to set up and did not require partners to invest in pricey new kit: “You just need a container that holds the microbes and makes sure they have contact with the methane. So on a dairy farm, the reactor can be a big plastic tub full of compost or biochar.
“If they have a manure lagoon, they need to put a cover over the lagoon and just add a pipe and a blower to push the gas into the container.”
In a landfill site, he said, “We grow the cells in liquid to produce our FOUNDATION fertilizer, which is more concentrated.”
According to Silverman: “We have had a large outpouring of customer interest globally. Everyone would like to make money from waste methane. Billions of cubic meters of methane are being flared or vented every year and 95% of people [that produce it] can’t do anything [profitable] with it.”
Further reading:
Waste methane to fertilizer: Windfall Bio trial shows yield bump in specialty crops
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