Frontier, a carbon removal marketplace co-founded by Google, Stripe, and Shopify, has purchased over 115,000 metric tonnes of carbon removal credits from geoengineering startup Planetary Technologies in a $31.2 million deal.
This marks Frontier’s first investment in ocean alkalinity enhancement (OAE), a novel method that differs from their usual focus on direct air capture and bioenergy carbon capture.
Planetary’s technology involves adding magnesium hydroxide, a compound commonly used as an antacid, to seawater via existing wastewater treatment plants and power station outfalls. This raises the ocean’s alkalinity, neutralising carbonic acid formed when CO2 dissolves in seawater and converting it into stable bicarbonate ions, effectively locking away carbon for centuries.
The oceans absorb around 25% of human-generated CO2 but have become 30% more acidic since pre-industrial times due to this carbon uptake—a threat to marine life like corals and shellfish. Planetary’s approach both reduces ocean acidification and increases the ocean’s capacity to take up more CO2.
Pilot projects in Nova Scotia and Virginia show promising results, with independent tests confirming increased alkalinity and reduced CO2 levels in seawater.
Planetary aims to scale this technology to remove over one billion metric tonnes of CO2 annually, while lowering removal costs from $270 to under $100 per tonne.
This approach utilises existing infrastructure to minimise environmental disruption and costs, offering a scalable, safe means of carbon removal that complements emission reduction efforts and helps restore ocean health.