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  • Writer's pictureKelvin Mureithi

Can Removing CO2 from the Ocean Help Mitigate Climate Change?


The (cold) ocean acts as a giant natural carbon dioxide (CO2) sponge, absorbing about 25% of the planet's carbon dioxide emissions.

Companies like Equatic and Captura Corp are proposing strategies to remove CO2 from the ocean—also known as Direct Ocean Capture or DOC. Both companies say they could eventually remove carbon dioxide from the ocean for around US$100 per tonne.

What's the core idea behind Direct Ocean Capture (DOC)?

Simply put—remove C02 from the ocean to make room for it to soak up even more.

Now of course the science and technology behind it is a lot more complex.

But, but, but: As with most engineering projects, this isn't a free lunch.

The process they've created consumes a good chunk of energy—about 2.2 megawatt-hours per tonne of CO2 removed. In Captura's case, renewables can be used to meet this energy demand. Additionally, about half of that energy cost can potentially be offset by the 35 kilograms of hydrogen produced per tonne of CO2. Boeing signed a deal in June to purchase 2,100 metric tons of green hydrogen from Equatic for sustainable aviation fuel.

The tech is still pretty new and has its sceptics.

As a United Nations panel put it:

“Engineering-based removal activities are technologically and economically unproven, especially at scale, and pose unknown environmental and social risks.”

Similarly, while I find the engineering behind this intriguing, I'm leaning towards what Mark Spalding, the head of the Ocean Foundation, has to say.

He believes there are many unknowns to invest heavily in this right now. We've got to be careful about altering the ocean's chemistry and pH levels. We don't know if pulling CO2 out will solve one problem but create another. So why not focus on solutions that are less risky and have a better shot at working?

If Direct Ocean Capture is still up for debate, there are other, less controversial ways to tackle the issue, like seagrass restoration and conservation.


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