Waste Methane to Fertilizer Startup Windfall Bio Auctions Off Assets

Windfall Bio, the methane-to-fertilizer startup backed by Amazon's Climate Pledge Fund, is auctioning assets after failing to secure Series B funding. The Silicon Review reports on the sale of bioreactors and intellectual property.

Windfall Bio, a California-based startup that raised $37 million to transform methane gas into organic fertilizer using methane-eating microbes, is auctioning off its assets after failing to secure additional funding. The auction includes bioreactors, laboratory equipment, and intellectual property.

The startup raised a 9 million seed round in 2023, followed by a 28 million Series A round in April 2024 led by Prelude Ventures. Major investors included Amazon's Climate Pledge Fund, Breakthrough Energy, Bessemer Venture Partners, Mayfield Fund, SOSV, and Global Brain. The company was in the process of raising a Series B round as recently as November 2025, but those efforts failed.

Windfall Bio had developed a technology using naturally occurring methane-eating microbes (MEMs) that convert methane into a nitrogen-rich organic fertilizer called Foundation. The fertilizer received Organic Materials Review Institute (OMRI) certification, making it eligible for use in organic farming.

The company had run pilot programs with Straus Family Creamery and Darigold, both suppliers to Whole Foods. It also partnered with Republic Services' Sunshine Canyon Landfill in Los Angeles to capture methane emissions. Field trials on Romaine lettuce showed yield increases of 23 to 34 percent compared to conventional feather meal fertilizer.

Founded in 2022 by Josh Silverman, who previously co-founded gas fermentation firm Calysta, Windfall Bio had 47 employees at its peak. The technology was designed to allow farms and landfills to convert their own methane emissions into fertilizer on-site, reducing both greenhouse gases and fertilizer costs.

The asset auction marks the end of a promising agtech venture. Windfall Bio had positioned itself as a solution to rising fertilizer costs amid global trade disruptions. However, the company could not secure the funding needed to scale from pilots to commercial operations.

As Windfall Bio auctions off its assets, The Silicon Review examines how a startup backed by Amazon's Climate Pledge Fund and Breakthrough Energy failed to reach commercial scale despite promising technology and strong field trial results.