A bold new effort to extract carbon dioxide from the Pacific Ocean as a way to combat climate change is backed by fossil fuel giants and Big Tech. But the nascent technology, dubbed “direct ocean capture” (DOC), still has a long way to go to prove it works — and won’t cause any new problems.
Caltech researchers founded the startup Captura, which just announced a new project today. Captura was founded in 2021 and won a $1 million prize from Elon Musk’s XPrize contest the following year. Now, with funding from the largest gas company in the US, Captura is building its largest pilot project to date at the Port of Los Angeles.
The idea is that filtering CO2 from seawater allows the oceans to absorb more greenhouse gases
The idea is that filtering CO2 from seawater will allow the oceans to absorb more of the greenhouse gas, keeping it out of the atmosphere where it would warm the planet. Since the industrial revolution, the world’s oceans have gobbled up nearly a third of human greenhouse gas emissions. Without that help, climate change would be much worse than it already is – with global warming already fueling more extreme weather disasters and threatening to wipe some coastal communities off the map.
The ocean’s CO2-sucking forces, as well as Captura’s technology, are based on a principle called Henry’s Law. It’s the same force that causes a drink to go flat after you pop open a can of beer or soda. The CO2 wants to flow from where there is a higher concentration to where there is a lower concentration of the gas so that there is equilibrium. As fossil fuels increased the concentration of CO2 in the atmosphere, oceans began to suck up more of the gas.
Captura’s technology aims to stimulate that process by extracting CO2 from seawater. First, the ocean water has to draw into the DOC plant. It then separates out about half a percent of that water and goes through a process called electrodialysis. That’s a fancy way of saying they zap the water with electricity to rearrange molecules into an acid and a base. When the acid is added back to the rest of the seawater, it reacts with the carbon to release CO2.
Captura can then capture that gas to store it somewhere or sell it as a product. Acidic water (which also happens to be a symptom of climate change) is very bad for marine life, so Captura adds the base to the water before releasing it back into the ocean. Now that the water is low in CO2, it can remove even more CO2 from the atmosphere.
Captura launched its first pilot in Newport Beach, California, last August. It unveiled today a new pilot project about 100 times larger at a public-private research facility called AltaSea in the Port of Los Angeles. The project should be able to remove about 100 tons of CO2 from the ocean every year. In the grand scheme of things, that’s still miniscule — equivalent to taking about 22 cars off the road for a year.
The goal is to test how the technology works in the real world and see if it has any unwanted side effects. “We want to make sure our impact on ocean waters is as benign as we think it is,” said Captura CEO Steve Oldham.
“We want to make sure our impact on ocean waters is as benign as we think.”
Some conservation groups are already wary of the technology. Captura plans to filter the water to prevent marine animals from being sucked into the DOC plant. Whether those filters are good enough to keep plankton out is a concern for Shaye Wolf, a climate science director at the Center for Biological Diversity with a background in ecology and ocean sciences. Plankton form the basis of the entire marine food web, meaning that many other animals depend on the microscopic organisms for their food. Then there are concerns about adding more industrial activity and noise pollution to already stressed marine ecosystems.
What happens to the CO2 Captura capture at the Port of Los Angeles is still up in the air. For now, Oldham says Captura will most likely sell the gas to other companies to use as an ingredient in commercial products such as concrete or carbon fiber. In the longer term, he envisions building commercial DOC plants on top of retired offshore oil and gas platforms where the CO2 they capture can be pumped under the seabed for permanent storage.
That prospect also worries Wolf. “That’s a big concern because oil and gas wells have a track record of spills and blowouts,” she says. The edge. “It is inevitable that CO2 pumped underground under high pressure will leak at some point.”
She is also skeptical about the technology as a climate solution because of Captura’s financiers. Southern California Gas, which prides itself on being the country’s largest gas company, is a major financier of the Port of Los Angeles project. The oil and gas giants Aramco and Equinor are also supporters of Captura.
“Across the board, the biggest lenders [of carbon removal] are the fossil fuel industry and partners. It eventually becomes an industry scam or an industry distraction from real climate action, rapidly reducing fossil fuel extraction and use,” says Wolf.
Prior to joining Captura in 2022, Oldham was the CEO of another startup called Carbon Engineering, which partners with oil giant Occidental to develop projects that filter CO2 from the air. Occidental plans to inject some of that carbon dioxide into oil fields to drive out hard-to-reach reserves to sell what it calls “net-zero” oil.
“I have no qualms about devoting my personal time to making this technology a reality, because it will be needed,” says Oldham. The edge of his work at Captura. He points to a United Nations climate report that includes carbon removal in possible pathways to meeting global climate goals set out in the Paris Agreement.
However, even carbon removal proponents warn that it is no substitute for avoiding greenhouse gas emissions by moving to clean energy. Carbon removal is most useful for tackling emissions from industries that cannot easily run on renewable energy, such as steel mills that typically use coal to heat furnaces to very high temperatures.
And yet companies of all kinds, especially Big Tech, are turning to technologies that seek to filter CO2 from the air and water to offset some of their emissions. Captura has contracted with Frontier, an initiative that Stripe, Alphabet, Meta, Shopify and McKinsey launched last year to make it easier for other companies to offset emissions from emerging carbon removal technologies. Through Frontier, Captura wants to sell carbon credits representing tons of CO2 from the ocean. The credits will most likely come from yet another pilot plant the startup plans to build next year.