Microsoft to buy 4.9 million metric tons of human waste for $1.7 billion. Here’s why

Vaulted Deep found in 2023 specialises in collecting contaminated bioslurry waste that’s too messy to reuse and piping it 5000 feet below the Earth’s surface. Once buried, the decomposition process stops, locking in methane and CO₂ that would otherwise be released into the atmosphere.

Daniel Sanchez, assistant professor of cooperative extension at the University of California-Berkeley said, “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.” “It’s as simple as one can get,” according to Sanchez, who specializes in biomass systems that remove CO2 from the atmosphere.

The startup’s method doesn’t just reduce greenhouse gases; it also prevents harmful chemical discharge from polluting soil and water systems. That double benefit waste management and climate action is exactly why Microsoft is investing.

Microsoft’s environmental idea comes at a time when its energy hungry AI operations are increasing its carbon emissions. Between 2020 and 2024, the company released 75.5 million tons of CO2. At the same time, its goal is to become carbon negative by 2030 and to remove more carbon than it can by 2050.

To hit that target, Microsoft is betting on a suite of experimental technologies. Vaulted Deep’s project joins a diverse carbon removal portfolio that includes reforesting Panama and capturing trash incineration emissions in Norway for storage beneath the North Sea.

Brian Marrs, Microsoft’s senior director of energy and carbon removal, said the tech giant invested in Vaulted Deep partly because of the co-benefits of the design. “Vaulted Deep is a waste-management company that’s become a carbon dioxide removal company,” he said.

Vaulted Deep’s origin is as unusual as its business model. Co-founders Julia Reichelstein and Omar Abou-Sayed never set out to launch a carbon removal company. Abou-Sayed’s father originally developed the underground injection technology to dispose of oil field waste. Later, Omar commercialised it under the company Advantek, working with bioslurry from a Los Angeles wastewater facility.

“I remember looking at him and doing a little bit of math and said, ‘I think you run like the largest carbon-removal project in the entire world that I’ve never heard of,’” she said. The conversation prompted the pair to create Vaulted Deep.

Today, the company handles about 20 per cent of LA’s biosolids and just opened a new facility in Hutchinson, Kansas. The plant fed by truckloads of agricultural and municipal waste is expected to remove 50000 tons of carbon annually at full capacity.

While some parts of the world, especially Europe, turn waste into biogas, North America and limited energy reuse infrastructure make Vaulted Deep’s strategy workable. And because the process uses standard drilling, no expensive, first of its kind tech, it’s considered low-risk and cost effective compared to alternatives like direct air capture.

Sanchez said that collecting and storing the waste currently costs around $150 per ton, but co-location with waste facilities could drive prices down further.