Podcast Summary: Turning Seawater into a Carbon Removal Solution with Captura

Podcast: Inevitable (an MCJ podcast)
Episode: Turning Seawater into a Carbon Removal Solution with Captura
Date: September 30, 2025
Host: Cody Simms
Guest: Steve Oldham, CEO of Captura

Overview

In this episode, Cody Simms sits down with Steve Oldham, CEO of Captura, to discuss direct ocean capture (DOC) technology—a novel approach that removes carbon dioxide (CO₂) from seawater, leveraging the ocean’s natural capacity to rebalance atmospheric CO₂. Oldham, who previously scaled Carbon Engineering to prominence in the direct air capture (DAC) sector, unpacks how Captura’s process is different: it requires no chemical inputs, produces no waste, and is highly energy-flexible, harnessing off-peak renewable energy.

The conversation covers the science behind ocean-atmospheric CO₂ exchange, technology specifics, regulatory hurdles, commercialization pathways, and Oldham’s pragmatic philosophy for climate tech at scale.

Steve Oldham's Journey in Carbon Removal

• Background

  • Began in mathematics and space/robotics in Canada.
  • Came to carbon removal by joining Carbon Engineering in 2017 when it was a scrappy startup (15 people, basic facilities).

    “…I joined Carbon Engineering…we had maybe 15 people at the time…I remember the facility was a pretty basic one. We had one toilet that ran continuously, never stopped…” —Steve Oldham (02:17)

• Carbon Engineering's Growth & Exit

  • Scaled Carbon Engineering to over 150 people, built the Squamish pilot plant, and partnered with Occidental (Oxy).
  • Led licensing deal and the design of Stratos, the world’s largest DAC plant.
  • Oxy acquired Carbon Engineering for $1.6B in 2023—the largest carbon removal exit to date.
  • Oldham transitioned to Captura before the exit was finalized.

    “Occidental…decided to acquire the company at a valuation of 1.6 billion in 2023…I still know a lot of the people there…and wish them all the best.” —Steve Oldham (04:06)

Understanding Direct Ocean Capture (DOC)

[Key segment: 05:30–13:12]

Why DOC?

• Problem with atmospheric CO₂ removal: Low concentrations (~420 ppm) require moving massive volumes of air, leading to complex and energy-intensive technology.
• DOC Alternative: The ocean holds much higher CO₂ concentrations—about 150 times that of air. By removing CO₂ from seawater, the ocean naturally pulls more CO₂ from the atmosphere to restore equilibrium—a process governed by Henry’s Law.

  “What we do is we let the ocean do the hard work. We let the ocean remove CO₂ from the atmosphere, and we take CO₂ out of the ocean instead.” —Steve Oldham (05:30)

Henry’s Law and the Soda Analogy

• Explained: There must be a balance between dissolved CO₂ in water and atmospheric CO₂.
• Soda can analogy: Opening soda releases excess CO₂ to the air; the same principle means taking CO₂ from seawater causes atmospheric CO₂ to dissolve back in.

  “If you take CO₂ out of the liquid, the atmosphere has to put it back. So that’s what we do at Captura.” —Steve Oldham (07:15)

Process at Captura

• Inputs/Outputs: Only energy and seawater go in; pure CO₂ and decarbonized water come out. No chemicals or waste are involved.

• Steps:

  1. Pull ocean water into plant.
  2. Soften a fraction (~0.5%) of it.
  3. Perform proprietary electrodialysis (not electrolysis) to split molecules and generate hydrochloric acid and sodium hydroxide.
  4. Use acid to liberate CO₂ from water; use degassing to capture it.
  5. Neutralize (re-add base), then return water to the ocean.

  “It’s just using liquids, a liquid to make the two, the acid and the base, and then put the acid in first, pull out the gas and put the base back in.” —Steve Oldham (11:48)

• Environmental impacts:

  • The process is benign to marine life and compliant with wastewater standards. Pilot plant effluent is tested for safety and even supports marine life.

Ocean Acidification and Local Benefits

• Deacidification: While large-scale global impact is limited by mixing speeds, local deacidification (e.g., in bays, coral reef zones) is a potential benefit.

  “…there's interesting applications, for example coral reefs, shellfish farming in localized areas where our process can…help de-acidify.” —Steve Oldham (12:34)

Deployment Models & Operational Considerations

[Key segment: 13:12–16:30]

Types of Deployments

• Onshore: Retrofit existing power stations or coastal facilities that already intake and discharge seawater.
• Offshore: Repurpose end-of-life tankers as floating DOC plants.
• Barges: Floating, barge-based deployments utilizing ocean currents to minimize energy use for pumping.

  “On a large maritime vessel, you can put about a million tons of carbon removal on an end of life vessel…It’s basically a floating platform for us.” —Steve Oldham (13:12)

Energy Use and Flexibility

• Main Operational Costs: Staffing and electricity.
• Tech advantage: Most energy is used in electrodialysis, not pumping.
• Load balancing: Can run electrodialysis during off-peak hours using surplus renewable energy, making energy cost-effective and flexible.

  “…We will power our system and use most of our energy when curtailed energy or off-peak energy is available. Reduces costs, makes us much more flexible.” —Steve Oldham (15:34)

Carbon Credits, Verification, and Utilization

[Key segment: 15:56–23:03]

MRV (Measurement, Reporting, Verification) and Carbon Accounting

• Measurement: CO₂ is physically measurable as a product output.

• Credit Issuance: Current protocols only issue carbon credits as the atmospheric drawdown occurs, which is modeled and may take 1–2 years for full equilibrium.

  “So we pull the CO₂ out of the water, we measure it, we provide it…but the carbon credit is generated when the equilibrium occurs…It might take, say, two years…” —Steve Oldham (16:30)

• Oldham’s Take: He argues immediate removal from the biosphere (atmosphere + ocean) should be credited right away, since atmospheric drawdown is inevitable—noting ocean health is improved instantly.

  “If it is a natural and inevitable follow on and you benefited the ocean, why am I not getting a carbon credit the day I take the CO₂ out and sequester it? Ultimately, removal from the biosphere is what matters.” —Steve Oldham (18:46)

Utilization vs. Sequestration

• Oldham’s Philosophy: Pragmatism over purism. If utilization (e.g., for synthetic fuels) accelerates deployment and cost reduction, it’s beneficial for the sector—even if ultimate sequestration is the long-term goal.

  “If that accelerates the deployment of the technologies, the development, the bringing down the cost curve…that’s a good thing.” —Steve Oldham (21:53)

• EOR (Enhanced Oil Recovery): Oldham acknowledges EOR was a motivator for Oxy’s DAC investment, but believes demonstrating DAC at scale (Stratos) is the real climate win—even if part of the initial use case is EOR.

  “…the pragmatist in me says we’ve moved the ball down the road. We’ve proven this technology at scale.” —Steve Oldham (24:16)

Policy and Incentives

• US 45Q credit: Captura doesn’t currently qualify as 45Q only rewards direct atmospheric removal; lobbying efforts continue to push for inclusion.
• Comparison to Other Ocean CDR: Unlike ocean alkalinity enhancement (which adds materials to the sea and faces scale and regulatory barriers), Captura’s process is closed-loop—no inputs, no dumping.

Industry Comparisons & Market Growth

[Key segment: 28:24–32:56]

Model for Scale: Renewable Energy Trajectory

• Phases:
  1. Prove technology (with government/early adopter support).
  2. Enable first deployments (need subsidies, risk-sharing).
  3. Reach commercial, predictable scale (project financing, cost reductions).

  “I would like to see that the CDR industry is able to follow a very similar trajectory to the renewable energy industry.” —Steve Oldham (28:34)

Adoption Drivers

• Missing compliance markets: US lacks strong regulatory mandates; large-scale customer adoption depends on regulation and proven cost-effective solutions.
• Public & Political Will: Getting buy-in requires making CDR less threatening than "lifestyle change" narratives.

Market Demand & Customer Segments

[Key segment: 32:56–35:07]

• Early adopters: Tech companies (Microsoft), airlines, shipping companies, Oxy (oil & gas).
• Heavy industry (cement, steel, chemicals): Not yet adopting CDR due to slim margins and lack of direct customer-facing pressure.

  “The technology industry has good margins…if you’re a steel maker…you’re a step away from the customer…So your role in not being carbon neutral is less visible to the customer.” —Steve Oldham (33:53)

Captura Today: Progress and Plans

[Key segment: 35:07–38:11]

Current Deployments

• Pilot facility: Kona, Hawaii—built from scratch in 70 days, fully operational, meeting KPIs.

  “We built that plant from scratch…in 70 days, fully commissioned. It worked first time…operating now for six, seven months…exactly on performance.” —Steve Oldham (36:12)

• Visitors’ access: Virtual tour available online.

• Product offtake: Some CO₂ supplied locally to aquaculture and dry ice industries, exploring food & beverage opportunities.

Next Steps

• Membrane/electrodialysis market: Technology also relevant for lithium mining, energy storage, desalination.
• First commercial plant: Likely in Europe due to investor support, infrastructure, sequestration options (e.g., Northern Lights).
• Capitalization: $47M raised to date; Series B in progress with backing from strategic partners (Equinor, Maersk, Aramco, Hitachi, European renewables).

Reflections on Legacy and The Future

[Key segment: 39:12–41:09]

• Success Formula: Building strong, complementary teams of scientists and business leaders.
• Vision: Wants to see DOC join DAC in proving out scalable, low-cost CDR to facilitate wider regulations and public acceptance.

  “…bringing an ocean solution and a air solution to the table, I think I’d be pretty happy with that. And if that means that we get wider adoption of CDR, recognition by the public and the politicians that this technology is ready…and we can start writing the regulations that we need for net zero, I’d be quite happy to have that.” —Steve Oldham (40:34)

Notable Quotes & Moments

• “I’m completely unqualified for the job that I have.”
  —Steve Oldham on his unconventional journey (02:17)

• “We let the ocean do the hard work.”
  —Steve Oldham on Captura’s core innovation (05:30)

• “If you take CO₂ out of the liquid, the atmosphere has to put it back.”
  —Steve Oldham, explaining Henry’s Law (07:15)

• “Any solution that’s trying to get to 10 billion tons a year…if you need 10 billion tons of input material, that’s going to be a challenge.”
  —Steve Oldham on the barriers for ocean alkalinity enhancement (27:47)

• “It’s on us, the carbon dioxide removal industry, to prove that we can be at large scale and cost effective.”
  —Steve Oldham on the need for actionable, scalable demonstrations (34:28)

• “We built that plant from scratch from bare earth in 70 days, fully commissioned. It worked first time.”
  —Steve Oldham on Captura’s Hawaii pilot (36:12)

Key Takeaways

• Direct ocean capture is emerging as a scalable, low-impact alternative to DAC, harnessing the ocean’s natural CO₂ exchange.
• Captura’s process is energy-flexible, closed-loop, and environmentally benign, with promising pilot success and ambitious plans for commercial deployment.
• Regulatory and carbon credit frameworks still lag DOC’s innovative reality, but strategic partnerships and technological validation are setting the stage for global scale-up.
• Oldham’s pragmatic philosophy emphasizes whatever pathways accelerate the scale and cost-effectiveness of carbon removal are valuable, with DOC positioned as a critical tool alongside DAC.

Key Timestamps

• Carbon Engineering origin story & Oxy exit: 02:17–04:43
• Introduction to direct ocean capture & Henry’s Law: 05:30–07:50
• Captura’s process, tech, and environmental impacts: 09:10–12:51
• Deployment models and energy strategy: 13:12–15:56
• Carbon credit protocol & measurement debates: 16:30–18:46
• Utilization vs. sequestration, EOR defense: 21:53–25:17
• DOC vs. ocean alkalinity enhancement: 27:06–28:24
• Pathways for scaling, renewable energy analogy: 28:34–30:09
• Market adoption, regulatory and public acceptance: 30:37–32:56
• Current deployment, pilot facility (Hawaii): 35:07–36:47
• Future plans, commercialization, financing: 36:50–38:11
• Legacy and CDR vision: 39:12–41:09

For more information and a virtual tour of the Hawaii pilot plant, visit Captura’s website.