Microsoft bets $1.7 billion on burying human waste to fight climate crisis

In one of the most unconventional climate bets to date, Microsoft has signed a $1.7 billion deal to bury human and industrial waste deep underground — not for recycling, but to lock away greenhouse gases that would otherwise be released into the atmosphere.

The tech giant’s 12-year agreement with U.S.-based startup Vaulted Deep will see 4.9 million metric tons of organic waste — including sewage sludge, manure, and paper mill byproducts — injected 5,000 feet below the Earth’s surface starting next year. The goal: halt decomposition, and with it, the release of methane and carbon dioxide.

The move underscores Microsoft’s accelerating investment in carbon removal technologies as it races toward its ambitious goal of becoming carbon negative by 2030 and removing all historical emissions by 2050. Between 2020 and 2024 alone, Microsoft emitted over 75 million metric tons of CO₂ — much of it driven by energy-intensive artificial intelligence operations.

“Vaulted Deep is a waste management company that’s become a carbon dioxide removal company,” said Brian Marrs, senior director of energy and carbon removal at Microsoft. “The co-benefits of this approach — climate action and pollution control — made it a compelling investment.”

Founded in 2023, Vaulted Deep specializes in handling bioslurry waste too hazardous or contaminated for reuse. Its process doesn’t involve fancy tech or futuristic machines — just standard drilling equipment and a simple, scalable idea: pump sludge underground and stop it from breaking down.

“It’s the sludgy waste — the stuff we really don’t have any other use for — and they want to inject it underground into permanent geological storage,” explained Daniel Sanchez, assistant professor of cooperative extension at UC Berkeley. “It’s as simple as one can get.”

That simplicity is key. Unlike high-cost options like direct air capture, Vaulted Deep’s method is relatively low-risk and financially feasible — currently costing around $150 per ton, with potential to drop further through co-located infrastructure.

The company already handles roughly 20% of Los Angeles’ biosolids and recently launched a second facility in Hutchinson, Kansas, which aims to remove 50,000 tons of CO₂ annually.

The startup’s origins are as unconventional as its solution. Co-founder Omar Abou-Sayed first applied the underground injection technology to dispose of oil field waste. But when his partner Julia Reichelstein realized the carbon-locking potential, the two pivoted toward climate solutions.

“I remember doing the math and thinking, ‘You’re running one of the world’s largest carbon removal projects — and nobody knows about it,’” Reichelstein recalled.

Microsoft’s investment in Vaulted Deep is part of a broader portfolio of carbon removal initiatives, including reforestation in Panama and capturing emissions from trash incineration in Norway for burial beneath the North Sea.

As climate pressures intensify and tech emissions surge, Microsoft is wagering that waste — even the dirtiest kind — can help clean up the planet.