Startup develops process powered by sunlight and seawater to remove CO2 from air: '[It] can actually be energy positive'

A Seattle-based startup called Banyu Carbon has developed a technology that can remove carbon dioxide from the air using sunlight and seawater, potentially helping to mitigate the overheating of our planet, Bloomberg reported.

While other methods of carbon removal already exist, a key issue with them is that they require large amounts of energy — either taxing already-limited clean energy resources or requiring additional carbon pollution to be created for their use. Banyu's method, on the other hand, purports to be low-energy and low-cost.

Per Bloomberg, the tech involves a unique molecule called a "reversible photoacid" that, when exposed to sunlight, releases acidifying protons that transform dissolved carbon dioxide in seawater into a gas that can be removed and safely stored. That decarbonized seawater can then be transferred back into the ocean, where it draws carbon dioxide from the atmosphere. As the reversible photoacid molecules can be reused, the process is cheap and sustainable.

Investors are taking notice. Banyu has raised around $8.5 million, with a large amount coming from the Grantham Foundation for the Protection of the Environment.

"Banyu is the only solution that we've seen that can actually be energy positive," Grantham Director Cyril Yee said, per Bloomberg. "There'll be engineering challenges for sure, but the basic science works, the chemistry works."

Carbon dioxide is the substance most responsible for the human-driven overheating of our planet — and the changing weather patterns and extreme weather that have come as a result.

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Most of the excess carbon dioxide and other heat-trapping gases in our atmosphere come from burning dirty energy sources like gas and oil, which is why scientists believe phasing out these fuels is the most crucial part of cooling down our planet. Carbon removal technology is seen as an important complement.

So far, per Bloomberg, Banyu has tested its technology only in lab settings and has yet to implement it at scale. It plans to establish a pilot program in Washington state this year that will remove tens of kilograms of carbon from seawater. If that is successful, the company has a contract with the Frontier fund to remove 360 metric tons (almost 400 tons) of carbon by the end of 2026.

While there are still a lot of unknowns around this new technology, such as any unintended effects that the photoacid will have on the ocean water, there are many reasons to be optimistic about this type of project.

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