Episode Summary
Executive Summary: Steve Oldham, CEO of Captura, explains direct ocean capture (DOC), a carbon removal approach that uses the ocean as the absorbent and energy-efficiently strips CO2 from seawater before the ocean re-equilibrates with the atmosphere. The discussion contrasts DOC with DAC, covers verification, deployment pathways, policy, and why Oldham sees both technologies as complementary routes to large-scale carbon removal.
Main Topics: Steve Oldham’s background in carbon removal (Priority: 5/5): Oldham traces a career from math and robotics to Carbon Engineering and then Captura, emphasizing startup-building experience and partnerships as critical to scaling carbon removal. How direct ocean capture works (Priority: 5/5): Captura removes CO2 from seawater using electrodialysis, acid/base chemistry, and degassing, then returns decarbonized water so the ocean naturally pulls more CO2 from the air. Comparison of DOC and DAC (Priority: 5/5): The conversation contrasts direct ocean capture with direct air capture, including thermodynamics, atmospheric/ocean equilibrium, and the different verification and scale challenges. Verification, MRV, and carbon credits (Priority: 4/5): Oldham discusses how DOC credits are modeled under current protocols, the lag between extraction and atmospheric drawdown, and why he believes ocean removal should count more directly. Deployment and scaling strategy (Priority: 5/5): Captura’s planned deployments include existing coastal infrastructure, offshore vessels, and barges, with off-peak renewable energy as a cost advantage and potential load-balancing benefit. Markets, policy, and commercialization (Priority: 4/5): The discussion covers offtake demand, 45Q eligibility, government policy, and Oldham’s view that CDR needs outcome-based regulation and pragmatic buyers across sectors. Capital, investors, and next steps (Priority: 4/5): Captura’s funding, strategic backers, pilot progress in Hawaii, and plans for a first commercial plant in Europe frame the company’s path toward project finance and broader deployment.
Key Arguments: Removing CO2 from seawater is easier to scale than from air because the ocean already contains far more dissolved CO2 and covers most of the planet. DOC can be a closed-loop process with no added chemical inputs and no waste products, making it potentially simpler and more sustainable than many other carbon removal pathways. Current DOC crediting methods rely on models of re-equilibration between ocean and atmosphere, but Oldham argues removal from the ocean should count immediately because atmospheric drawdown is inevitable. Using off-peak or curtailed renewable electricity can significantly reduce DOC costs and make the technology a flexible grid-balancing load. Captura’s approach is designed to be deployable in multiple formats: onshore at existing seawater-intake sites, on offshore ships, and on barges. Oldham views carbon removal as an infrastructure industry that will need government support, early adopters, and eventually outcome-based regulation to scale. He is pragmatic about utilization pathways: sequestration, synthetic fuels, and other uses can all help build the market, though he sees permanent storage as the clearest long-term climate outcome. Compared with ocean alkalinity enhancement or enhanced rock weathering, DOC avoids adding material to the ocean and avoids dependence on large input-material supply chains.
Data Points: Atmospheric CO2 concentration: 420 ppm - Oldham cites atmospheric CO2 levels to explain why extracting CO2 from air is hard. Ocean CO2 concentration relative to air: ~150x higher - Used to justify why extracting CO2 from seawater is more scalable than from air. Ocean share of emissions uptake: ~30% - Oldham says the ocean absorbs about 30% of human emissions. Carbon Engineering team size at his start: ~15 people - Oldham describes joining Carbon Engineering when it was still very small. Carbon Engineering scale at exit era: ~150 people - Company grew substantially before the Oxy acquisition. Carbon Engineering acquisition value: $1.6 billion - Occidental acquired Carbon Engineering in 2023, which Oldham cites as the largest carbon removal exit to date. Captura capital raised to date: ~$47 million - Funding total mentioned for Captura, including strategic investors. Pilot plant build time: 70 days - Oldham says Captura built and commissioned its Hawaii pilot plant from bare earth in this time. Pilot plant operating time: 6-7 months - The Hawaii pilot had been operating for months at the time of the interview. Pilot plant validation: Hundreds of hours - Oldham says the plant has run for hundreds of hours on performance. Potential vessel capacity: ~1 million tons of carbon removal - Oldham says an end-of-life maritime vessel could host this scale of capacity. First DOC credit protocol: Published earlier this year - He references Isometric’s first DOC carbon credit protocol. Modeled drawdown timing: ~2 years - Oldham says modeled atmospheric re-equilibration may take around two years. Rapid drawdown fraction: ~80% - He states most drawdown occurs quickly, with the rest slower to reach 100%. Energy share from off-peak/curtailed power: ~70% - Oldham says Captura can use mostly off-peak energy by overbuilding electrodialysis capacity.
Pivotal Quotes: "We let the ocean do the hard work." — Steve Oldham: Explaining the core advantage of direct ocean capture over direct air capture. "No added material and produces no waste products." — Steve Oldham: Describing Captura’s closed-loop process and sustainability claims. "I’m an environmental pragmatist." — Steve Oldham: Summarizing his approach to climate tech, markets, and acceptable CO2 end uses.
Implications: DOC could materially expand carbon removal if its MRV, policy treatment, and project finance mature. The interview suggests ocean-based capture may lower costs and scale faster than DAC, especially with renewable-energy integration and strong strategic partners.