This article was originally featured on Hakai Magazine, an online publication about science and society in coastal ecosystems. Read more stories like this at hakaimagazine.com.
Cutting carbon emissions is not enough to keep global warming to less than 1.5 °C—the goal of the 2015 Paris Agreement on climate change. Not anymore, at least. Unless the transition from fossil fuels to renewable energy generation speeds up considerably, climate scientists say that removing carbon dioxide and other greenhouse gases from the atmosphere will be essential to closing the gap and keeping planetary heating under control. As a result, hundreds of start-ups pledging to remove greenhouse gases from the air and water have popped up within the past few years.
While land-based carbon dioxide removal projects have been undergoing testing and development for decades, ocean-based carbon removal is a more recent arena in the push to combat climate change. And one of the leaders in that field—Equatic—is about to ramp up its efforts in a big way.
What began three years ago as a US Department of Energy–funded research project out of the University of California Los Angeles has already grown into a pair of pilot projects in Los Angeles and Singapore. And now, the company has its sights set on building a massive marine carbon capture facility in Quebec that—once completed—will rival the world’s largest terrestrial carbon removal facilities.
In a statement, Equatic said it is working with Montreal-based carbon removal developer Deep Sky. Equatic says it chose Quebec for its plant because building there would offer access to renewable electricity and because of the province’s decarbonization plans. Yet whether at the still-in-development Quebec plant, which Equatic hopes will get under construction soon and become operational in 2027, or at its existing test facilities, the company’s process for capturing carbon works the same way.
It begins by pumping seawater into a tank and then using an electrical current to electrolyze the water. That splits the water molecules into oxygen and hydrogen gases and extracts an alkaline slurry. This solution is then reacted with the air, which pulls carbon dioxide out of the atmosphere and chemically transforms it into two byproducts. One, calcium carbonate, is a white powder used in agricultural lime. The other is a bicarbonate solution that gets released back into the ocean. Previous research suggests carbon stashed away like this should be stable for millennia and would no longer contribute to global warming.
What sets the proposed Quebec plant apart is its scale. Equatic’s Singaporean pilot facility has 10 electrolyzers and can process 4,000 tonnes of carbon each year. The planned Quebec facility, meanwhile, will house 300 electrolyzers capable of churning through 110,000 tonnes annually—about as much carbon as is emitted by 24,000 cars.
To make a big enough dent in the global carbon balance to keep warming to less than 1.5 °C, carbon capture efforts need to somehow remove tens of gigatons of carbon from the atmosphere each year, according to the United Nations’ Intergovernmental Panel on Climate Change. So if the technology catches on, a facility like Equatic’s—which could tackle roughly 0.001 percent of that amount—is just the beginning. (Such scant-seeming returns are typical in the climate engineering space, proving how much harder it is to put the genie—or, in this case, the carbon—back into the bottle.)
Edward Sanders, Equatic’s chief operating officer, says the company’s approach has multiple advantages over other existing carbon capture technologies. Compared with efforts to capture carbon directly from the air, “the net energy intensity of the process is low,” Sanders says. He also says that accurately measuring how much carbon the facility is locking away long-term is easier than with other marine carbon removal approaches, such as kelp farming. “We do all the measurement and carbonation on land, so we can accurately record the extent of the carbon dioxide removal,” Sanders says.
Equatic is moving ahead alongside other carbon-capture companies, such as fellow California-based Captura and Ebb Carbon. In its own pilot project in Los Angeles, Captura used electricity and seawater to draw carbon dioxide out of the water. It then returned the carbon dioxide–depleted seawater to the ocean, where it caused even more carbon dioxide from the atmosphere to dissolve into the water. Captura plans to run a final test next year in Hawai‘i using a process that the company expects can capture some 1,000 tonnes of carbon dioxide annually—at least to start. Tara Bojdak, Captura’s communications director, says that once that pilot project is complete, the company will be looking to scale up to a large commercial plant.
For its part, Ebb Carbon will soon begin running its own electrodialysis-based pilot plant in Port Angeles, Washington, where it will remove 500 tonnes of carbon dioxide from the atmosphere annually for two years.
In the long term, Captura hopes to build carbon capture equipment alongside existing water-processing infrastructure, especially desalination facilities. Desalination produces lots of salty brine, Bojdak says, that could be fed straight into Captura’s electrodialysis system, allowing the company to skip some filtration and other steps and make the process faster. “Our technology and business model are all about how we can get to that large scale and low cost and do it as quickly as possible, so we can start to have a bit of an impact on climate change,” Bojdak says.
As bigger and more industrial marine carbon removal projects move forward, Sara Nawaz, an environmental social scientist and carbon removal policy expert at American University in Washington DC, argues that transparency and communication with residents in areas where these facilities are being considered will be critical in allaying people’s concerns. In her own work, surveying people in British Columbia and Washington State and talking to environmental and Indigenous groups, Nawaz says that people have a lot of uncertainty about marine carbon dioxide removal. In fact, she says, many people she surveyed hadn’t yet heard of it. But for those who had, “there’s a mix of real concern about ecological impacts, and also hope that this is something that could be a positive thing for their communities.”
People are worried, says Nawaz, that industrial marine carbon dioxide removal could affect coastal ecosystems such as coral reefs, mangroves, and particular fisheries. However, research on the techniques’ environmental effects—whether positive or negative—is in the early stages. Some people also expressed political and economic concerns, including about who will own these technologies and whether marine carbon dioxide removal is an actual climate solution or mere greenwashing.
Around the world, scientists and start-ups are exploring a vast range of marine carbon removal strategies, including shellfish aquaculture, seaweed farming, alkalization, rewilding whale populations, and protecting coastal ecosystems such as seagrass meadows and mangrove forests. And, after numerous reports of failing or underperforming forestry projects intended to offset carbon emissions, some start-ups are prioritizing accurate measurements of how much carbon they can actually remove.
Philip Boyd, a marine ecologist at the University of Tasmania in Australia and the cochair of a United Nations climate working group on ocean-based climate interventions, says that, among scientists, “the consensus is [that] chemical methods to sequester carbon in the ocean are probably the most promising.”
“That’s not to say they’re not without some hurdles and issues,” Boyd adds. “But they’re certainly relatively simpler than systems that rely on the manipulation of ecosystems or biology.”
That’s also the view of Jaime Palter, an oceanographer at the University of Rhode Island who, in her own research, is exploring the effectiveness and ecological safety of various ocean-based carbon removal approaches. “People tend to think growing kelp sounds so safe and easy, but chemical manipulation, like ocean alkalinity enhancement, sounds scary,” says Palter.
Large-scale kelp farming, however, involves directly changing the ecosystem, says Palter. She argues this makes it riskier than chemical approaches because an abundance of kelp would take nutrients that could otherwise be used by phytoplankton. That could affect the wider food web since many species depend on phytoplankton. She also echoes Equatic’s argument that, with chemical methods, it’s easier to verify the amount of carbon being removed.
Ultimately, though, the fledgling industry is swirling with unknowns. So far, research on marine carbon removal has been based on small-scale lab experiments and trials. So as Equatic’s pending Quebec plant moves ahead, scientists will be watching to learn more about its environmental consequences—and about just how much of a dent marine carbon dioxide removal can really make.
This article first appeared in Hakai Magazine and is republished here with permission.