Frontier coalition backs ocean carbon removal solution in US$31mn deal

Members of the Frontier coalition have signed a US$31 million collective offtake agreement with a firm generating carbon removals from an ocean alkalinity enhancement project.

Frontier members will pay project developer Planetary US$31.3 million to remove 115,211 tonnes of CO2 between 2026 and 2030 by adding dissolved alkaline minerals to seawater, reducing ocean acidity.

The offtake agreement was facilitated by Frontier on behalf of Stripe, Google, Shopify, McKinsey Sustainability, Autodesk, H&M Group, Workday, Aledade, Canva, Match Group, Samsara, SKIMS, Skyscanner, Wise, and Zendesk.

Hannah Bebbington, Head of Deployment, Frontier: “Ocean alkalinity enhancement can remove CO2 from the atmosphere extremely cheaply and efficiently. But expanding it beyond small-scale trials calls for ironclad measurement and safety protocols, alongside addressing community concerns. Planetary is taking on these challenges head on with a rigorous MRV approach and thoughtful community engagement at their Tufts Cove site. This is the right project and team to pave the way forward for this promising pathway.”

Ocean alkalinity enhancement cost curve

Planetary’s process involves adding dissolved alkaline minerals, such as calcium oxide or magnesium oxide, into coastal surface waters, boosting the ocean’s ability to drawdown carbon by converting dissolved CO2 into stable bicarbonate ions, which are durably stored in the ocean for over 10,000 years. 

The company uses existing coastal facilities like power plant cooling water outfalls to ensure quick and effective integration without the need for massive new infrastructure investment. 

Ocean alkalinity enhancement is said to have the potential to remove several billion tonnes of CO2, with a credible path to under US$100 per tonne – though the coalition is paying around US$271 per credit in the deal announced this week. Planetary says the path to lower cost is contingent on switching to lower-cost alkaline feedstocks and co-locating facilities near these feedstock sources to cut transportation costs.

‘Cheapest and most scalable carbon removal solution’

Frontier has supported the deployment of alkaline materials across a range of environments to help clarify the efficacy, scalability and safety of each approach: on land with firms Lithos, Eion and Terradot, in freshwater systems like rivers and wastewater treatment with CarbonRun and CREW, and now in a coastal environment with Planetary.

With this deal, Planetary is expanding on a pilot project that recently delivered the world’s first verified OAE credits, and initiating the next phase of operation with deliveries starting in 2026.  The offtake agreement also includes binding commitments to share project data publicly, further advancing the development of these ocean-based carbon removals.

Mike Kelland, CEO of Planetary, added: “This offtake with Frontier buyers allows us to demonstrate that ocean alkalinity enhancement can safely and effectively remove CO2 beyond small-scale trials. This approach could be the cheapest and most scalable carbon removal solution. We're eager to show how it can be rolled out responsibly.”