Microsoft has signed a five year carbon removal credit agreement with biochar firm Carba. The agreement will see Microsoft purchase 44,000 tons of carbon removal credits over the specified period.
“We’re thrilled to contribute to Microsoft’s portfolio by providing high-quality carbon removal credits that will be retired starting in 2025,” said Andrew Jones, CEO, Carba. “Our fully integrated approach - combining biomass sourcing, processing, and secure storage - enables us to scale quickly while having the potential to deliver significant community co-benefits.”
Carba has developed a novel pyrolysis technology that utilizes a thermal battery to produce “high-quality, high-yield biocarbon for industrial inputs and landfill burial,” according to its website. The company claims that its method converts waste biomass and organic materials into stable biocarbon for use in materials, pollution management, and permanent carbon dioxide removal.
Carba will use the biochar as an alternate daily cover and bury it in local landfills, which it claims protects it from degradation and possibly provides further environmental co-benefits. Carba says the properties of the biochar have the potential to act like an activated carbon filter within the landfill, which can reduce odors, remediate pollutants, and increase gas pollutant absorption.
Reflecting on the agreement, Brian Marrs, senior director for Energy & Carbon Removal at Microsoft said: “By colocating biomass supply chain delivery, pyrolysis, and end-use & storage, Carba’s biochar burial offers the potential to become a scalable and cost-effective climate solution.
“This agreement with Carba allows us to better explore the future of this biochar end-use and the possible co-benefits, while benefiting from the near-term delivery of these credits with a straightforward monitoring and verification process.”
Founded in 2021, Carba is headquartered in Minneapolis, Minnesota. Its first deployment is with a waste disposal company converting municipal wood waste into biocarbon for use as daily cover in the landfill. Last year, the company received a $7 million grant from the US Department of Energy for a Carbon Negative Shot Pilot. In addition, its project methodology has been certified by Isometric, a carbon removal standard and registry, following a 30-day public consultation.
The agreement is the latest Microsoft has signed with a biochar firm over the past two years. Last March, Microsoft signed a six-year carbon removal deal to purchase 95,000 tons of credits from The Next 150 in Mexico.
Before this, in December 2023, it agreed a deal with Exomad Green, the world's largest producer of biochar, for 32,000 tons of carbon dioxide removal credits. In addition, it also signed an agreement with Carbon Streaming to buy credits from its biochar site in Virginia.
In 2025 alone, Microsoft has signed removal agreements with reforestation firm Living Carbon for 1.4 million tons of credits, carbon capture firm CO280 for 3.685 million tons of carbon removal credits, and Enhanced Rock Weathering company Terradot for 12,000 tons of carbon removal credits.
