A bold new attempt to take carbon dioxide out of the Pacific Ocean as a way to combat climate change is being backed by fossil fuel giants and Big Tech companies. However, the emerging technology, called “direct ocean capture” (DOC), still has a long way to go to prove it works – and won’t cause new issues.

Researchers from the California Institute of Technology (Caltech) founded the startup Captura, which announced a new project. Founded in 2021, the company already won a million dollar award at Elon Musk’s XPrize competition in 2022. Now, with funding from the largest gas utility in the US, Captura is launching its largest pilot project to date at the Port of Los Angeles.

The idea is that filtering CO2 from seawater will allow the oceans to absorb more greenhouse gas, keeping it out of the atmosphere where it would heat up the planet. The world’s oceans have soaked up nearly a third of human greenhouse gas emissions since the Industrial Revolution. Without it, climate change would be much worse than it already is – with global warming already causing more extreme weather disasters and threatening to wipe some coastal communities off the face of the Earth.

The ocean’s ability to suck up CO2, as well as Captura’s technology, rely on a principle called Henry’s Law. It’s the same force that causes a carbonated drink to evaporate when exposed to air. CO2 flows from places of higher concentration to places of lower gas concentration until equilibrium is established. Therefore, as fossil fuels raised the concentration of CO2 in the atmosphere, the oceans started drawing in more of the gas.

Captura’s technology aims to stimulate this process by sucking CO2 out of seawater. First, it has to pull ocean water into the DOC plant. Then it separates about half a percent of that water and starts the electrodialysis process. In other words, they hit the water with electricity to redistribute the molecules into an acid and a base. When the acid is returned to the rest of the seawater, it reacts with the carbon and releases CO2.

Captura can then “capture” that gas to store it somewhere or sell it as a product. Acidic water (which is another symptom of climate change) has a very bad effect on marine life, so Captura adds the base to the water before releasing it back into the ocean. This creates a lack of carbon dioxide in the water so it can draw even more from the atmosphere.

Captura launched its first project in Newport Beach, California last August. Now it unveiled a new pilot project that’s about 100 times larger at a public-private research facility called AltaSea at the Port of Los Angeles. The project should be able to remove about 100 tons of CO2 from the ocean per year. In the larger context, this is still insignificant – 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 check for unwanted side effects. “We want to make sure that our impact on the ocean water is as benign as we believe it is,” says Captura CEO Steve Oldham.

Some environmental groups are already wary of the technology. Captura plans to filter the water so that sea animals are not sucked into the DOC plant. But whether those filters are fine enough not to pull in plankton is the concern of Shaye Wolf, a climate science director at the Center for Biological Diversity with a background in ecology and ocean sciences. Plankton form the foundation of the entire marine food chain, meaning that many other animals rely on these microscopic organisms for nutrition. In addition, there are concerns about increased industrial activity and noise pollution in already stressed marine ecosystems.

It is still unknown what will happen to Captura’s carbon dioxide capture at the Port of Los Angeles. For now, Oldham says Captura will most likely sell the gas to other companies that will use it as an ingredient in commercial products like concrete or carbon fiber. In the long term, the CEO envisions building commercial DOC plants on decommissioned oil and gas platforms where the CO2 they capture could be pumped under the seabed to permanently sequester it.

That possibility also worries Ms. Wolf. “That’s a major concern because oil and gas wells have a track record of leakages and blowouts,” she tells The Verge. “It’s inevitable that CO2 that’s pumped at high pressure underground is going to leak at some point.”

She is also skeptical of the technology as a climate solution because of Captura’s investors. Southern California Gas, considered the largest American gas utility, is the main funder of the project at the port of Los Angeles. Oil and gas giants Aramco and Equinor are also backing Captura.

“Across the board, the biggest backers [of carbon removal] are the fossil fuel industry and partners. It ends up being an industry scam or an industry distraction from real climate action, which is rapidly reducing fossil fuel extraction and use,” maintains Wolf.

Before joining Captura in 2022, Steve Oldham was the CEO of another startup called Carbon Engineering, which works with oil giant Occidental to develop projects that filter CO2 from the air. Occidental plans to dump some of that carbon dioxide into oil fields to push out hard-to-reach reserves and sell what it calls “net-zero” oil.

“I have no qualms whatsoever about spending my personal time trying to bring this technology into reality because it’s going to be needed,” Oldham told The Verge about his work at Captura. He also points to a United Nations climate report that includes carbon removal as a potential pathway to achieving global climate goals set by the Paris Agreement.

However, even decarbonization advocates caution that it is no substitute for curbing greenhouse gas emissions by switching to clean energy. Decarbonization is most useful for addressing emissions from sectors that cannot easily run on renewable energy, such as steel mills that typically use coal to heat furnaces to very high temperatures.

And yet, various companies, especially Big Tech, are turning to technologies that seek to filter CO2 from air and water to neutralize some of their emissions. Captura has a contract with the Frontier initiative, launched last year by Stripe, Alphabet, Meta, Shopify and McKinsey to make it easier for other companies to offset emissions through new carbon removal technologies. Through Frontier, Captura intends to sell carbon credits in the form of tons of CO2 taken out from the ocean. The credits will most likely come from another pilot plant that the startup plans to build next year.