Ebb Carbon wants to pull CO2 from the sky with electricity and seawater

At a waterfront lab in Sequim Bay, a quiet inlet on Washington’s Olympic Peninsula, the startup Ebb Carbon is trying to answer a crucial question for the climate: Can we supercharge the ocean’s role as a carbon sink to help limit global warming?

The California-based company recently began operating its novel ​“marine carbon dioxide removal” system at the Sequim facility, which is run by the Department of Energy’s Pacific Northwest National Laboratory (PNNL). Ebb’s technology uses electrochemistry to split saltwater into its acidic and alkaline parts. The long-term plan is to return alkalinity to the ocean, creating chemical reactions that pull CO₂ from the air and store it safely in the sea.

“We’re essentially accelerating a natural process,” Ben Tarbell, CEO and co-founder of Ebb Carbon, told Canary Media. ​“So instead of taking millions of years [to happen], it takes weeks to months.”

On Monday, the two-year-old startup unveiled its first-of-a-kind demonstration project, which is designed to remove 100 metric tons of CO₂ per year at full capacity. Along with PNNL, Ebb is partnering with research institutions such as the National Oceanic and Atmospheric Administration and the University of Washington to better predict how its system could work at scale — and how it could potentially affect ocean ecosystems.

Ocean-based approaches are gaining traction within the burgeoning field of carbon dioxide removal, a process that’s considered ​“unavoidable” in fighting climate change. While countries must prioritize phasing out fossil fuels and reducing greenhouse gas emissions, those steps aren’t likely to be enough to avoid the worst effects of a warming planet, according to the U.N. Intergovernmental Panel on Climate Change.

Solutions for removing CO₂ — including using giant air filters, injecting ​“bio-oil” underground and transforming mining waste — are all relatively nascent, and they all face significant scientific and technical barriers to scaling up. Even so, government agencies and private investors are plowing funding into these fledgling technologies in the hopes of making it easier and cheaper to draw down planet-warming carbon.

Earlier this month, the Department of Energy awarded a total of $1.1 billion to two ​“direct air capture” hubs along the U.S. Gulf Coast, with two more hubs slated to be announced next year. The agency also said it plans to offer funding to a variety of carbon-removal pilot projects, including five ocean-based systems. The program’s overarching goal is to enable ​“gigaton scales” of CO₂ removal and storage by 2050, up from perhaps thousands of tons today.

For new outfits like Ebb, supersizing their projects isn’t the only challenge. Companies and researchers are still figuring out how to accurately quantify and verify just how much CO₂ they’re locking away, and for how long. That information is key to knowing whether projects will ultimately benefit the climate — especially if businesses plan on selling carbon-removal ​“credits” or ​“offsets” to other entities.

“The momentum is really just getting going around using the ocean as a climate solution,” said Christian Meinig, who leads the coastal sciences division at PNNL. ​“These are still early days, and we’re really going to learn a lot in these coming years.”

Harnessing the ocean to lock away CO₂

Ocean-based carbon removal strategies typically fall into one of two categories.

“Biotic” approaches rely on photosynthetic organisms to soak up carbon from the atmosphere and store it as biomass. For example, the Israeli companies Rewind and BlueGreen Water Technologies are taking discarded plant matter and harmful algal blooms, respectively, and sinking them to the bottom of the sea. Ocean fertilization, a theoretical and controversial idea, calls for sprinkling nutrients like iron over seawater to grow CO₂-absorbing phytoplankton.

The second category, ​“abiotic” approaches, involves harnessing the seawater itself. Artificial upwelling refers to pumping nutrient-rich water from the deep ocean to the surface so it can absorb carbon, a process that would naturally happen over longer periods of time. Electrochemical techniques aim to use electricity to either enhance seawater’s ability to store carbon — or to directly extract CO₂ from the ocean.

Equatic, a spinout of UCLA’s Institute for Carbon Management, is working on that last approach. 

Earlier this year, the startup began operating pilot-scale plants in Los Angeles and Singapore, each of which can not only remove 100 kilograms of CO₂ per day from seawater — they can also produce smaller amounts of hydrogen. The company plans to trap the extracted CO₂ into calcium carbonate, which can be used in low-carbon building materials, and sell the hydrogen to industrial facilities, or use it to power their own process.

Equatic’s closed-system design enables it to track and monitor carbon ​“so that we know exactly what is happening before anything leaves the plant,” said Edward Sanders, the startup’s chief operating officer. ​“That’s quite a different approach” from other ocean-focused efforts, he added.

Ebb Carbon, meanwhile, is ramping up testing on its new demonstration project.

Since launching in 2021, Ebb has raised over $25 million in seed and venture capital funding to develop and deploy its electrochemical system, which can fit inside a 20-foot shipping container.

The technology builds on years of research led by Matt Eisaman, the company’s CTO and co-founder, who recently joined Yale University’s Center for Natural Carbon Capture as a faculty member. Eisaman first met Tarbell, a former SolarCity executive, several years ago when both were working with Alphabet’s innovation arm, X.

Ebb plans to partner with existing sites that already process seawater, such as desalination plants or aquaculture facilities. The company will intercept some of the saltwater and, using electricity, run it through a stack of ion-selective membranes. The device then rearranges the salt and water molecules to produce two streams — one acidic (hydrogen chloride) and the other alkaline (a dilute form of sodium hydroxide). The acid is kept on land, while the alkaline seawater flows back out through the site’s wastewater system.

When alkalinity is added to seawater, it reacts with the CO₂ in the atmosphere to become bicarbonate, a form of carbon that can stay trapped in the sea for thousands of years — without increasing the ocean’s acidity. On a local level, some amount of alkaline seawater might even act as an antacid to protect marine life from increasingly hostile waters.

The ocean has absorbed roughly 30 percent of the carbon dioxide released by humans since the Industrial Revolution, which is causing ocean acidification that harms coral and shell-forming animals and disrupts fish behavior. Human-caused climate change is also partly the reason why Earth’s oceans are now the hottest they’ve ever been in modern history, scientists say.

Ocean-based solutions need more science

Still, given how fragile marine ecosystems are already, some environmental groups are pushing back against pursuing technological fixes that could disrupt the ocean’s delicate balance even further, calling instead for more urgent action to reduce greenhouse gas emissions. While each type of ocean-based CO₂ removal carries its own potential risks, they all share a common challenge: a lack of well-established research.

Carbon180, a nonprofit that advocates for carbon-removal solutions, says it ​“doesn’t endorse or oppose” any ocean-centric methods because so little is known right now about how effectively they’ll work at removing CO₂, or how they might impact marine environments and the coastal communities that depend on them.

“We don’t really have the data sets to say what is going to happen if we do gigatons of ocean-based carbon dioxide removal,” said Anu Khan, Carbon180’s deputy director of science and innovation. She said that designating a federal agency to oversee these types of projects could make it easier to coordinate research, funding and, eventually, permitting and regulations.

The efforts now underway in Sequim Bay are an important early step toward addressing the sector’s many unknowns, Meinig said.

At PNNL’s waterfront lab, intake pumps draw thousands of gallons of Pacific Ocean water into large circular tanks. While Ebb’s earliest experiments used table salt and water, the ongoing study is using ​“biologically alive” seawater replete with microorganisms.

Scientists are using sensors and software controls to measure how acidic or alkaline the water is once it runs through the electrochemical system, and to understand how much CO₂ is turning into bicarbonate. In a smaller aquarium, they’re also testing to see how organisms like sea slugs, isopods and oysters fare when exposed to varying pH levels, said Nicholas Ward, an earth scientist based at PNNL’s Sequim lab.

The data is used to inform sophisticated computer models, which help predict what’s likely to happen when the system is deployed at larger scales and in real-world conditions. Later steps will involve testing the technology in the bay, using buoys to measure how much alkalinity the system is adding to the seawater and assessing how the ecosystem responds.

Ebb Carbon and PNNL didn’t share the total cost of the research project. But the two-year initiative has received funding from the National Oceanic and Atmospheric Administration’s Ocean Acidification Program, the Department of Energy’s Water Power Technology Office, the National Oceanographic Partnership Program and the nonprofit ClimateWorks Foundation.

The PNNL researchers said they hoped their lab could establish a ​“center of excellence” of sorts in the future to serve the growing tide of carbon-removal companies looking to test and validate their ocean-based technologies.

“We need to be doing this [carbon removal] at speed and scale,” Meinig said. ​“However, in order to go fast, we might have to start slow…and invest in the research to do so responsibly and effectively.”