In a nutshell: A Los Angeles startup is making waves by claiming it can simultaneously address two major climate challenges: removing carbon dioxide (CO2) from the atmosphere and storing it in the ocean, while also producing emissions-free hydrogen fuel. The concept sounds promising, but not everyone is on board with it. Equatic says its novel technology can strip CO2 directly from the atmosphere and lock it away in the depths of the sea for millennia. At the same time, it generates green hydrogen that could one day replace fossil fuels in sectors like shipping, aviation, and heavy manufacturing.The company is part of a growing number of startups exploring ocean-based carbon removal as an alternative to underground storage methods like carbon capture and sequestration. But Equatic says it's the only one producing hydrogen in the process.The company has a unique approach: a proprietary electrochemical system running on clean electricity first converts seawater into hydrogen gas, oxygen gas, an acid stream, and an alkaline slurry. The slurry absorbs CO2 when exposed to air. The captured CO2 is discharged back into the ocean as stable mineral compounds meant to lock it up for 10,000 years or more.With global emissions continuing to soar, many scientists believe technological intervention will be needed to actively strip CO2 back out of the atmosphere to meet climate goals. That's where startups like this come in. Equatic initially experimented with small pilot barges off the coasts of Singapore and Los Angeles. Since then, it's been scaling up rapidly.The BBC reports that a major new plant in Singapore, said to be the world's largest ocean carbon removal facility, is currently under construction. It will have over 100 times the capacity of the prototypes, capturing an expected 4,000 tons of CO2 and churning out around 100 tons of hydrogen annually. // Related StoriesThen there's a much bigger commercial plant planned for Quebec, Canada, which could start operating as soon as 2026. This will boast a capacity to remove over 100,000 tons of CO2 and generate 3,600 tons of hydrogen each year.As for how Equatic plans to make money, well, the goal is to sell the CO2 it captures as carbon offset "credits" to companies aiming to achieve net-zero emissions. These companies would essentially pay Equatic to remove CO2 from the atmosphere on their behalf as a way to offset their own emissions.However, the concept of ocean carbon removal is stoking concerns from environmental groups. Last year, over 400 scientists signed a letter warning that large-scale tampering with ocean chemistry could have unpredictable and potentially devastating impacts on marine ecosystems.Last year, over 400 scientists signed a letter warning that large-scale tampering with ocean chemistry could have unpredictable and potentially devastating impacts on marine ecosystems.Critics also argue that banking on future carbon removal could undermine urgently needed cuts to greenhouse gas pollution today. And carbon offset programs in general have been plagued by credibility issues and doubts about their real climate impacts.Equatic acknowledges the measurement challenges and has revamped its technology to keep the CO2 capture process in a closed-loop system that it says will make accounting and verification easier. The company also insists its method is designed to comply with regulations and operate within existing environmental permits.Edward Sanders, the CEO of Equatic, argues scalability is key. He told the BBC that the company's approach could theoretically remove up to 20% of current global CO2 emissions if around 1,200 large facilities were deployed by the mid-2040s.