The Controversial Machine Sending CO2 to the Ocean and Making Hydrogen

Equatic is among a wave of start-ups exploring how the ocean could be harnessed to capture and store carbon. But not everyone is sure it's such a good idea.

Many scientists now think at least some carbon capture and storage technology will be needed to prevent dangerous temperature rise.

A separate challenge, but just as relevant to climate change, is the scale-up of green hydrogen, which is often viewed as the key to replacing fossil fuels in areas like industry, shipping and aviation—although current production is miniscule.

So LA-based start-up Equatic's claim to have created an ocean-based carbon removal machine that can tackle both these hurdles at once has an obvious appeal.

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"We have a technology that does two things pretty well," says Edward Sanders, chief executive of Equatic. "One is we take CO2 out of the atmosphere and we store that permanently. The second thing we do is produce green hydrogen."

Equatic is among a wave of companies exploring how the ocean could be harnessed to capture and store carbon in the long term, as an alternative to the more common proposal of injecting it into rocks below the Earth's surface. It's the only company, it says, which is also producing green hydrogen in the process.

Unrelenting global emissions have led many scientists to believe we now need to intervene to take large amounts of CO2 back out of the atmosphere.

However, not everyone thinks ocean-based carbon removal is such a good idea. "Marine CO2 removal is simply too risky," says Mary Church, geoengineering campaign manager at the Center for International Environmental Law (CIEL), a non-profit environmental law firm based in Geneva, Switzerland. "It could alter ocean chemistry, causing changes in nutrient levels and species abundance, with significant consequences for ecosystems."

Others are concerned about the feasibility of marine carbon removal, and whether it could really put a significant dent in emissions.

With tens of millions of dollars now pouring into companies like Equatic, marine carbon removal is rapidly moving up the climate agenda. Critics argue regulators, and the rest of us, need to catch up.

The ocean has already been a vast and often unacknowledged ally in protecting humans from climate change. It has absorbed more than 90% of the heat generated from our greenhouse gas emissions and absorbs at least a quarter of our CO2 emissions. How much more CO2 it will store naturally in the future is now a subject of intense scientific interest.

Ocean-based carbon removal would similarly attempt to store additional carbon in the ocean, but it has not yet been widely used or thoroughly tested. It is on the rise, however, with tens of millions of dollars pouring into the sector, including from some of the biggest names in tech, such as Microsoft and Shopify, as well as several airlines.

"The ocean is so vast, natural storage is a key advantage [over land-based techniques]," says Sifang Chen, a science and innovation advisor at Carbon180, a Washington-based non-profit which advocates for CO2 removal solutions. "It's more cost efficient to store the removed CO2, and we don't need the same infrastructure like pipelines that we do for direct air capture."

HYPE METER

Equatic has developed an interesting novel technology which it has demonstrated with several pilot plants and is now building a larger plant capable of removing 4,000 tonnes of CO2 and producing around 100 tonnes of hydrogen a year. Its process can durably store carbon in the ocean for thousands of years, according to the company and other marine carbon removal advocates.

However, some experts are concerned tampering with the ocean could impact the marine environment, including in unforeseen ways. Critics also say shifting focus to CO2 removal from the atmosphere could risk end up distracting from necessary CO2 emissions cuts.

Equatic's process works like this: first, it pumps sea water into an electrolyser, a machine that uses electricity to split water into hydrogen and oxygen, which in Equatic's case is run on clean electricity such as wind, solar or hydro. This converts the seawater to hydrogen gas, oxygen gas, an acid stream and an alkaline slurry of calcium and magnesium-based materials. The alkaline slurry is exposed to air, pulling out CO2 and trapping it, then discharged into the sea. A last step is to neutralise the acid waste stream using rocks (in order to avoid ocean acidification) before this is discharged into the sea too.