Microsoft and waste management solutions startup Vaulted Deep announced today a new long-term offtake agreement, with Vaulted Deep delivering up to 4.9 million tonnes of durable carbon dioxide removal over 12 years through its process of storing organic waste deep underground, marking one of the largest-ever carbon removal deals globally to date.

Spun out of injection well-focused waste management company Advantek in 2023, Vaulted Deep partners with municipalities, industrial operators, and agricultural producers to manage their organic waste that can’t be reused or safely applied to land. The company sequesters sludgy organic wastes, including biosolids, manure, agricultural, food waste, and paper sludge – which would otherwise be incinerated, landfilled, or spread on land, resulting in the release of CO2 back into the atmosphere – and injects the carbon-rich biomass deep underground for permanent storage. Vaulted Deep turns the waste into a carbon-rich slurry, and utilizes a proprietary slurry injection technology to inject the carbon deep underground, offering 10,000+ year permanence.

According to Vaulted Deep, the new deal with Microsoft, which will run through 2038, will allow the company to expand its approach to new sites across the U.S., with the company actively looking for new waste partners across industries to tackle their hard-to-manage organic waste.

Julia Reichelstein, co-founder and CEO of Vaulted Deep, said:

“As carbon removal moves beyond pilots and prototypes, there is growing demand for solutions that can scale safely and address real-world problems. Vaulted offers a dual solution: it meets urgent waste management needs and drives measurable climate and public health improvements. This agreement reflects a broader shift in how carbon removal is being deployed. It is no longer limited to emerging technologies but is increasingly delivered through large-scale existing infrastructure with novel applications.”

The agreement marks the latest in a series of large-scale carbon credit deals by Microsoft, by far the largest corporate buyer of carbon removal credits globally, including several multi-million ton agreements announced in just the past few weeks, as part of the tech giant’s efforts to become carbon negative by 2030. According to carbon dioxide removals (CDRs) platform CDR.fyi, the new agreement brings Microsoft’s carbon removal purchases to over 30 million tonnes, well ahead of the Frontier buyers group as the second largest purchaser at 1.4 million tonnes.

Brian Marrs, Senior Director of Energy and Carbon Removal at Microsoft, said:

“Vaulted Deep provides a differentiated, scalable approach to permanent carbon removal with low technology risk. Its work delivers immediate climate benefits while stimulating local economies and addresses long-standing environmental challenges that communities face every day. We support this solution as part of our broader effort to accelerate durable, high-integrity carbon removal.”