Carbon removal startup Planetary has signed a landmark $31 million offtake agreement with a group of major global companies, including Stripe, Google, Shopify, McKinsey Sustainability, Autodesk, H&M Group, and Workday. Facilitated by the Frontier buyer coalition, the deal represents the largest-ever commitment to Ocean Alkalinity Enhancement (OAE) as a carbon removal technology.

115,000 Tons of Carbon Removal Through Ocean Chemistry

Under the agreement, Planetary will deliver 115,000 tons of carbon dioxide removals between 2026 and 2030. The company’s process captures CO₂ from the atmosphere and stores it in ocean water through a method that mimics natural mineral processes. The technology not only sequesters carbon but also addresses ocean acidification by increasing seawater’s alkalinity.

Planetary’s solution involves adding a pure antacid to coastal waters. This neutralizes carbonic acid and transforms the dissolved CO₂ into stable salts that remain locked in the ocean for over 10,000 years. By lowering CO₂ levels in seawater, the process allows more atmospheric carbon to be absorbed, amplifying the natural air-sea exchange cycle.

Expansion of Tufts Cove Pilot Project

The new funds will accelerate the next phase of Planetary’s operations, expanding its pilot program at Tufts Cove in Nova Scotia. This site was the first to deliver verified tons of carbon removal via OAE, marking a major step forward in real-world deployment of ocean-based solutions.

Mike Kelland, CEO of Planetary, called the agreement a breakthrough for the sector.

“This offtake with Frontier buyers allows us to demonstrate that ocean alkalinity enhancement can safely and effectively remove CO₂ beyond small-scale trials,” said Kelland. “We believe this could be the most scalable and cost-effective carbon removal approach, and we are committed to deploying it responsibly.”

Massive Scale Potential and Marine Ecosystem Benefits

Frontier, which helps channel corporate climate funding into early-stage carbon removal technologies, praised Planetary’s model for its potential to scale to billions of tons annually. Removal costs are projected to range from $50 to $160 per ton, with the added benefit of reducing ocean acidification and improving marine health.

Key to the deal is Planetary’s robust measurement, reporting, and verification (MRV) framework. This includes controlled dissolution of alkaline minerals before ocean release, alongside real-time sensor tracking and advanced modeling to monitor impacts. These steps help overcome one of the main barriers to ocean-based carbon removal: verifying long-term climate benefit.

Broader Corporate Support Through Watershed Partnership

Beyond the direct corporate buyers, additional firms will join the initiative through Frontier’s partnership with enterprise climate platform Watershed. This extended group includes companies such as Aledade, Canva, Match Group, Samsara, SKIMS, Skyscanner, Wise, and Zendesk.

Hannah Bebbington, Head of Deployment at Frontier, highlighted the importance of responsible scaling.

“Ocean alkalinity enhancement can remove CO₂ cheaply and efficiently,” said Bebbington. “But doing it at scale requires rigorous safety protocols and strong community engagement. Planetary is setting the standard with its MRV strategy and local collaboration at Tufts Cove. This is the right team to lead the way.”

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