Brine, Carbon, and the Economics of Audacity
Every day, desalination plants around the world pump millions of gallons of hypersaline brine back into oceans and brine ponds. It is expensive, environmentally fraught, and largely considered a cost of doing business - an inconvenient byproduct of turning seawater into something drinkable. Ethan Cohen-Cole looked at that brine and saw a carbon removal engine hiding in plain sight.
That insight - simultaneously obvious and invisible until someone with the right mental model arrived - sits at the core of Capture6, the Berkeley-based Public Benefit Corporation Cohen-Cole co-founded in 2021. The company uses salt extracted from desalination wastewater as a feedstock for a liquid sorbent that traps CO2 from ambient air. Electrochemistry splits the salt into a base and an acid; the base absorbs atmospheric carbon dioxide, forming stable carbonates that are stored permanently. Fresh water is recovered. Hydrochloric acid and calcium carbonates are sold as green chemicals. Carbon credits flow from the verified removals. The plant's costs - already necessary for brine disposal - now generate multiple revenue streams.
It is not magic. It is industrial chemistry, carefully arranged. The arrangement took someone who understood revenue models as well as he understood electrochemistry - which is where Cohen-Cole's bizarre career arc becomes relevant.
"The entire process could run on renewable energy, enabling net negative CO2 with revenue generation through carbon credits."- Ethan Cohen-Cole, CEO of Capture6
The Economist Who Ended Up in a Lab
Cohen-Cole arrived at climate tech by a route that would perplex most startup accelerators. He holds a BA in History from Harvard, an MPA from Princeton's Woodrow Wilson School, and a PhD in Economics from the University of Wisconsin-Madison - the kind of credential stack that gets you invited to central bank advisory committees, not cleantech pitch nights.
That's precisely where he spent the next fifteen years. As a financial economist at the Federal Reserve Bank of Boston, Cohen-Cole led quantitative reviews of large bank risk models and served as a designated system expert on risk management under Basel II. He advised the Bank for International Settlements on the drafting of Basel I and II. Three central banks consulted him on systemic risk management. His academic work during this period - research on consumer credit access, financial networks, and capital markets - accumulated 2,534 citations.
His most unexpectedly viral paper asked whether obesity spreads through social networks the way a virus does - a 2008 study in the Journal of Health Economics, co-authored with Jason Fletcher. It had nothing to do with banking and everything to do with a mind that refuses to stay in its lane.
After the Fed, Cohen-Cole moved to Vega Economics in Berkeley as Senior Advisor and Managing Director, providing financial and economic analysis for legal disputes and international organizations. By 2021, he had spent 25 years as a professor, regulator, policy analyst, and litigation consultant. Then he co-founded a desalination company.
The Technology: One Process, Four Products
Capture6's core technology threads four separate value chains through a single integrated system. Understanding it requires setting aside the usual assumption that carbon capture is expensive because it produces nothing. Capture6 produces four things at once:
How the System Works
The elegance here is structural. Most direct air capture startups must justify their existence purely on the value of the carbon removed - and carbon credit markets, while growing, remain volatile. Capture6 layers water recovery revenue and chemical sales on top, dramatically improving unit economics. The brine disposal costs that water utilities are already paying become the feedstock budget. Cohen-Cole has essentially built a business where the customer's existing cost becomes his company's raw material.
Projects on the Ground
Capture6 operates with a deliberate geographic spread - projects in California, Western Australia, New Zealand, South Korea, and the Middle East simultaneously. The two flagship demonstrations:
Project Monarch
Partnership with Palmdale Water District. Designed to remove approximately 25,000 tons of CO2 per year when fully operational. Replaces up to 100 acres of brine ponds. Projects 40% savings in lifetime costs. Advancing to Phase 2 with financing secured from RSF | Regenerative Social Finance.
Project Wallaby
Partnership with Pilot Energy Limited in the Midwest Clean Energy Project. Addresses acute water scarcity in a stressed region while integrating carbon removal and water recovery. Designed to co-produce green hydrogen and permanently sequester CO2. Vision to evolve into a full-scale commercial facility.
The $49 Million Bet
In March 2025, Capture6 closed a $27.5 million Series A - the company's largest round to date - bringing total funding to approximately $49 million. The lead investor was Tetrad Corporation, the family-owned investment company founded by the late Walter Scott Jr. Co-investors included Hyundai Motor Group's ZER01NE Ventures, Energy Capital Ventures, Elemental Impact, Bridge Investment, Sopoong Ventures, and Third Derivative.
The institutional backing was supplemented by over $8 million from the California Energy Commission - the largest award issued in that CID Program round - and additional U.S. Department of Energy funding. The government grants signal something that pure venture capital can't: that regulatory bodies with engineering staff have looked at the technology and concluded it works.
Recognition: The World Noticed
Cleantech has a thousand startups with beautiful slide decks. Recognition from independent expert panels is something different. Capture6 has accumulated a notable set:
The Partnerships That Signal Seriousness
In 2024, Capture6 signed a global collaboration agreement with Veolia Water Technologies & Solutions - the world's largest water treatment company - to deploy carbon dioxide removal facilities with integrated water management systems across five continents. Veolia's involvement brings engineering scale, distribution relationships, and decades of operational expertise in filtration, membrane, and electrodialysis technologies.
Separately, Rothschild & Co announced a long-term carbon removal partnership with Capture6. When a 180-year-old financial institution with a climate desk decides to make a multi-year commitment to a 4-year-old startup, it's worth noting.
"We built an aggressively scalable framework for direct air capture technology deployment to avoid the worst scenarios of global warming while creating freshwater."- Ethan Cohen-Cole, in interview with Scott Amyx (2024)
Career Timeline
Why This Matters Beyond the Hype
Carbon capture is a field littered with technically credible ideas that died on the economics. The reason most direct air capture startups struggle to scale is straightforward: removing CO2 from air is expensive, and the only buyer is the carbon credit market, which pays intermittently and at prices that rarely justify the capital cost of the plant. The typical response is to lobby for larger subsidies. Cohen-Cole's response was to build a system where removal is a byproduct of something customers already need and are already paying for.
Water is that thing. Roughly 3.6 billion people live in areas experiencing water scarcity for at least one month per year. Desalination capacity is expanding globally, and with it, the brine disposal problem. Every new desalination plant is, in Capture6's framing, a potential carbon removal site with a built-in customer (the water utility) and an existing feedstock budget (the brine disposal line item).
This is not a bet on voluntary carbon markets maturing. It's a bet that water utilities will pay to solve their brine problem - which they already do - and that the carbon removal, green chemicals, and additional fresh water are free revenue on top. The carbon capture startup that doesn't need carbon prices to work is genuinely unusual.
Cohen-Cole's background as a bank regulator - someone who spent 17 years stress-testing financial models for failure modes - may be precisely why the business model is structured the way it is: layered revenue, multiple off-take agreements, no single point of commercial failure. The physicist builds the most elegant machine. The economist builds the one that survives contact with the market.