When Ethan Cohen-Cole stepped away from a career analyzing economic data at the Federal Reserve Bank of Boston, he wasn't looking to fix just one environmental problem. He wanted to fix two at once.
On March 11, 2025, his San Francisco Bay Area company, Capture6, closed a $27.5 million Series A and project funding round to do exactly that: convert the salty wastewater from desalination plants into fresh drinking water while simultaneously pulling carbon dioxide out of the atmosphere. It's an audacious premise, coupling two revenue streams—water sales and carbon credits—in a single electrochemical process.
Tetrad Corporation led the round. Hyundai Motor Group's ZER01NE Ventures joined, alongside Energy Capital Ventures, Elemental Impact, Bridge Investment, Sopoong Ventures, Third Derivative, Stan & Jane Rodbell, and the Jacob S. Shapiro Foundation. Rothschild & Co, which had already signed on as a long-term carbon credit purchaser last November, served as financial advisor this time around.
Perhaps more than anything, the timing feels deliberate. The World Economic Forum warns that global freshwater demand will outstrip supply by roughly 40% come 2030. Meanwhile, desalination operations worldwide churn out some 142 million cubic meters of brine every single day—a disposal headache that often ends in evaporation ponds or ocean discharge, neither of which solves much of anything.
The Chemistry, Simplified
Capture6's technology hinges on an electrochemical trick. Take brine—the ultra-salty byproduct of desalination—and run it through the company's system. Sodium chloride gets split into sodium hydroxide and hydrochloric acid. The sodium hydroxide then reacts with atmospheric CO2, forming sodium carbonate, which locks the carbon away. Along the way, the company says it recovers "over 50%" of the water that would otherwise be lost as waste.
The result: freshwater for utilities, carbon removal credits for corporate buyers, and chemicals that can loop back into water treatment processes. No brine ponds required.
It's elegant on paper. The question, as always, is whether it pencils out at scale.
Cohen-Cole, who holds a PhD from Wisconsin, co-founded Capture6 in 2021 with Luke Shors. The pair structured it as a public benefit corporation, with offices in California and New Zealand—a geography that reflects the company's international ambitions as much as its founders' networks.
From Pilots to Projects
The new capital will fund expansion across a pipeline that already spans four continents, though much of the work remains in demonstration or early commercial phases.
Project Monarch, in Palmdale, California, broke ground on June 20, 2024, at the Pure Water Antelope Valley indirect potable reuse facility. The California Energy Commission had already kicked in $8.15 million in non-dilutive funding before this round. Then on April 22, 2026, Capture6 secured additional project-level financing from RSF Social Finance—supported by the California Infrastructure and Economic Development Bank—to advance Monarch's second phase. The company's planning documents call for approximately 4.5 million gallons of purified water per day and 25,000 tons of CO2 removal annually once the system is fully commissioned. Those are targets, not guarantees.
Across the Pacific, Project Wallaby is embedded within Pilot Energy's Mid West Clean Energy Project in Western Australia. Last July, Capture6 partnered with Isometric, a carbon credit verification outfit, to measure and report removal claims from the Australian site—a necessary step if the company intends to sell credits into voluntary carbon markets.
In South Korea, Capture6 is collaborating with K-water and BKT on what the partners are calling the world's first desalination brine-based direct air capture testbed. That project was announced in June, though details on capacity and timeline remain vague.
The Crowded CDR Field
Capture6 is hardly alone in pursuing ocean-and-brine-based carbon removal. Equatic, spun out of UCLA, uses seawater electrolysis to capture CO2 while co-producing hydrogen; pilots in Los Angeles and Singapore aim for commercial scale by next year. Captura, a Caltech spinout, pursues what it calls Direct Ocean Capture using electrodialysis, though without the water recovery angle. Ebb Carbon takes yet another tack, employing electrochemical ocean alkalinity enhancement with desalination brine as feedstock.
What sets Capture6 apart—at least in theory—is that dual value proposition: water utilities get a disposal solution and a freshwater source, while also generating carbon credits to offset their own emissions or sell into compliance and voluntary markets. Whether that bundled pitch proves more attractive than competitors' approaches remains an open question.
The company does hold a recently granted U.S. patent for "Carbon Dioxide Capture," listing Cohen-Cole and CTO Rahul Surana as inventors. Surana, who joined in May 2022, brings a chemical engineering PhD from Penn State and an academic pedigree that complements Cohen-Cole's economics background.
Early Market Signals
Capture6 has already secured some validation from the carbon removal market's gatekeepers. In September 2024, Frontier—the advance market commitment initiative backed by Stripe, Alphabet, Shopify, McKinsey, and others—facilitated a pre-purchase of 1,000 tons of CO2 removal by Shopify and Stripe. It's a modest tonnage, but a meaningful signal that buyers are willing to bet on the technology before it's fully proven.
Other partnerships have followed. Capture6 announced a collaboration with Veolia Water Technologies & Solutions in late 2024, and CNBC featured the company last June, highlighting potential cost advantages in water-stressed regions where desalination is booming but disposal costs are climbing.
Last October, the company was selected as a qualified team in the $119 million XPRIZE Water Scarcity competition—another stamp of credibility in a field where hype often outpaces hard data.
What Comes Next
With the Series A closed and project financing in hand for Monarch's second phase, Capture6 is moving out of the lab and into the messy reality of commercial deployment. The company's ambitions stretch across the United States, South Korea, New Zealand, Australia, and the Middle East—regions where water scarcity and decarbonization pressures are colliding.
But ambition is one thing. Execution is another. Capture6 must now prove its technology can operate reliably at commercial scale, deliver the promised water recovery rates, and generate carbon credits that satisfy increasingly rigorous verification standards. The capital is there. The partnerships are forming. The real test begins when the first large-scale plants come online and the meters start running—gallons produced, tons removed, dollars earned.
In climate tech, that's the moment when abstractions become accountabilities. And when investors, utilities, and corporate carbon buyers find out whether the chemistry actually works outside a PowerPoint deck.
