Making Room for Carbon

Sam Baker talks to Steve Oldham, CEO of Captura, about pioneering carbon removal from the ocean and the challenges ahead

THE OCEAN is already one of the planet’s most powerful carbon sinks, quietly absorbing around a third of human CO2 emissions since the 1990s. So why would anyone want to remove carbon from it?

For Steve Oldham, CEO of direct ocean capture (DOC) startup Captura, the answer is simple: because the ocean’s capacity to absorb more depends on chemistry. Under Henry’s Law, the concentration of CO2 in the air and in seawater moves towards equilibrium. As atmospheric emissions slow – or even stabilise – the rate of ocean uptake will follow.

“You’re not absorbing more CO2 into the ocean,” Oldham says. “You’re making room for the ocean to take more out of the atmosphere.”

Originally from Greater Manchester, Oldham joined Captura in 2022. He studied computer science at the University of Birmingham, spent 20 years in the Canadian space industry and joined direct air capture (DAC) developer Carbon Engineering in 2018, later acquired by Occidental Petroleum.

“Growing a business in carbon removals is not dissimilar to space technology,” Oldham says. “When you build a satellite, you spend an awful lot of money on the ground without knowing it’s going to work. You send it off into space, you cross your fingers, you hope it works. In carbon removals, you’re spending a lot of money building a plant, creating regulation and establishing a market for the first time.”

Carbon removal technology, which includes both DOC and DAC, differs from post-combustion carbon capture and storage. It extracts CO2 already present in the atmosphere or ocean rather than catching emissions at source. While post-combustion carbon capture works well in cement and power, it is harder to integrate into steelmaking or some chemical processes. Aviation, Oldham points out, cannot realistically decarbonise without carbon removals. “You’re not going to be capturing the CO2 at the back of an aeroplane”, and sustainable aviation fuel remains far from deployable at scale.

Oldham argues that DOC is far more efficient than DAC. “It’s simpler and cheaper to take CO2 out of the ocean and let the ocean do the hard work of taking it out of the air,” he says, noting that CO2 is around 150 times more concentrated in seawater than in air.

Closed-loop technology