Turning Seawater into a Carbon Removal Solution with Captura

Steve Oldham is CEO of Captura. Captura develops Direct Ocean Capture (DOC) technology that removes CO₂ from seawater, triggering the ocean to draw more CO₂ from the air to rebalance. With CO₂ concentrations ~150× higher in seawater than air, Captura’s closed-loop process uses electrodialysis to create acid and base on site—no added chemicals, no waste—and can run largely on off-peak renewable energy. 

Oldham, former CEO of Carbon Engineering, contrasts DOC with DAC, discusses MRV and crediting, deployment pathways (onshore, barges, vessels), his company’s pilot progress in Hawaii, and why pragmatic scale-up and licensing partnerships matter for gigaton carbon removal. 

Episode recorded on Aug 28, 2025 (Published on Sept 30, 2025)

In this episode, we cover: 

• [02:17] Steve’s path from Carbon Engineering to Captura
• [05:30] How Direct Ocean Capture actually works
• [09:10] Closed-loop design with no waste products
• [10:14] Using electrodialysis to split acid and base
• [13:12] Deployment options: onshore plants, barges, vessels
• [14:39] Running on off-peak and curtailed renewables
• [16:30] Measuring and crediting carbon drawdown
• [21:53] Balancing CO₂ use vs. permanent storage
• [25:22] Policy gaps like 45Q for ocean removal
• [35:15] Captura’s Kona pilot built in 70 days
• [37:33] First commercial project expected in Europe

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*Editing and post-production work for this episode was provided by The Podcast Consultant