With AI data centers' need for vast amounts of power threatening its commitment to be carbon negative by 2030, Microsoft has turned to innovative carbon removal strategies—including one that involves sending human waste deep underground. The company has signed a 12-year contract with Vaulted Deep, a company that grinds up "bioslurry," including waste from city sewage systems, and injects it 5,000 feet underground, the Wall Street Journal reports. At that depth, it won't decompose and release methane and carbon into the atmosphere.
TechCrunch describes Vaulted Deep as operating like a "reverse oil company." It injects the waste into porous rocks using technology developed for fracking. The bioslurry also includes excess manure from farm fields and waste from paper mills, which would otherwise have been incinerated or gone to landfills. "We're taking different types of organic waste," chief executive and co-founder Julia Reichelstein tells the Journal. "It's sludgy, often contaminated organic waste that today causes problems above ground, and instead we take the waste and put it really deep underground for permanent carbon removal."
Brian Marrs, Microsoft's senior director of energy and carbon removal, says the "co-benefits" approach of offsetting emissions and removing waste attracted the company to Vaulted Deep, which he describes as a "waste management company that's become a carbon dioxide removal company." The Vaulted Deep deal involves 4.9 million metric tons of carbon removal. Microsoft has already bought 59 million tons of removal through other projects this year.