Microsoft signs deal with ocean carbon removal project operating on Washington’s coast

Microsoft today announced a deal with a marine carbon removal startup on the northern edge of Washington’s Olympic Peninsula to potentially lock away up to 350,000 tons of CO₂ over the next decade.

Ebb Carbon uses a technology already employed by winemakers and in sewage plants that can be applied to the ocean, creating water that is chemically more basic than acidic. The basic or alkaline water can capture carbon from the ocean and safely store it — which also helps combat ocean acidification.

The agreement starts with 1,333 tons of removal, with the option for Microsoft to buy more removal credits. The companies did not disclose the terms of the deal.

“The ocean is a critical part of the carbon cycle,” said Brian Marrs, senior director of Energy and Carbon Removal at Microsoft, in a statement. “Ebb has developed technology to leverage the natural attributes of the ocean — its massive surface area and natural ocean processes that already pull CO₂ from the atmosphere — to durably remove and store large volumes of atmospheric carbon.”

Ebb Carbon is based in South San Francisco and partnering with the Department of Energy’s Pacific Northwest National Laboratory (PNNL) in Sequim, Wash., for its pilot plant. The company launched four years ago and has raised $22 million from investors.

At least 18 startups are turning to the ocean as a partner in taking carbon out of circulation — including another venture in the Pacific Northwest. Researchers at the University of Washington launched Banyu Carbon, which uses a different approach to tweaking ocean chemistry for carbon removal.

The strategy used by Ebb Carbon is called “ocean alkalinity enhancement.” Creating basic conditions in the seawater allows it to convert CO₂ into bicarbonate ions.

Microsoft has inked numerous carbon removal deals. Its first long-term agreement was signed in 2022 with Climeworks, which has built removal devices in Iceland. In July, Microsoft bought 500,000 metric tons of removal credits from a subsidiary of Occidental Petroleum in what was deemed the largest single carbon removal agreement ever made.

The tech giant based in Redmond, Wash., has ambitious climate goals and was starting to make progress towards them — until the use of artificial intelligence and generative AI exploded. Now it and the other data center giants are building energy-chugging facilities to meet the increased computation demands. Those efforts are driving up their climate impacts.

The carbon offset and removal sector has faced its own recent challenges. The space has been criticized for questionable accounting and verification of how much carbon it deserves credit for capturing. Ebb Carbon is working with the carbon registry Isometric to verify its impacts. Isometric is the first organization to create a protocol addressing carbon removal through ocean alkalinity enhancement.

Companies aiming to extract carbon dioxide from seawater face multiple challenges, oceanographer David Ho previously told GeekWire. That includes accurately monitoring, reporting and verifying the volume of carbon dioxide removed. When carbon is subtracted from sea water, the ocean gains new capacity to absorb it from the air, but that amount can be hard to calculate.

At the same time, Ho, who co-founded [C]Worthy to address marine carbon dioxide removal accounting, sees the overall approach as “having a better chance to scale” than land-based strategies.

“It’s great to see Microsoft and Ebb using Isometric’s first of its kind Ocean Alkalinity Enhancement (OAE) protocol to verify carbon removal,” said Stacy Kauk, Isometric’s chief science officer. “OAE is promising because of the vast surface area of the ocean. This same fact requires careful monitoring, reporting and verification.”