An electrochemical system that uses seawater to capture CO2 emissions offers a potential solution to address climate change more efficiently and cost-effectively than existing air capture systems. Engineers at MIT have developed an ocean capture system that captures CO2 from seawater, using a bismuth electrode to produce a bismuth compound and protons that convert bicarbonate ions back into CO2 gas. The concentration of dissolved CO2 in seawater is over 100 times higher than in air, making the ocean capture system more efficient and economically feasible, with costs ranging from $50-$100 per tonne of CO2. Once CO2 is extracted from the seawater, it can be turned into fuels, chemicals, and materials, or it can be permanently stored underground. The team is patenting their ocean capture system and plans to deploy it worldwide as independent ocean capture plants. The article also includes the top five keywords relevant to the content: ocean capture system, seawater, carbon dioxide, CO2 emissions, electrochemical system.
Seawater could be a potential solution to reducing atmospheric carbon dioxide levels and address climate change more efficiently than current methods of capturing it from the air, according to engineers in the US. Oceans and surface waters have been significant carbon sinks, absorbing about 30% to 40% of carbon dioxide emissions since the industrial revolution began. The engineers from the Massachusetts Institute of Technology (MIT) have developed an electrochemical system that uses seawater to capture CO2 emissions. Carbon dioxide reacts with seawater to create carbonic acid, which can then dissociate to form bicarbonate ions. The MIT system then converts the bicarbonate ions back into CO2 gas, which can be collected.
The ocean capture system uses a bismuth electrode that reacts with the chloride ions present in saltwater, producing a bismuth compound and protons. The resulting protons increase the water’s acidity, breaking down the bicarbonates and reforming CO2. The water is then returned to its original pH before releasing it back into the ocean. This technique enables the seawater to capture more CO2 from the air, as removing CO2 from the oceans drives more CO2 to be absorbed by the water, thereby reducing its concentration in the atmosphere.
The MIT team claims that the ocean capture system could be more efficient and cost-effective than air capture systems because the concentration of dissolved CO2 in seawater is over 100 times higher than in the air. A preliminary cost analysis shows that this technology could be economically feasible, with costs ranging from $50-$100 per tonne of CO2. Comparatively, one air capture system was calculated to cost $600 per tonne of CO2 in 2020.
The electrochemical system using seawater could offer a new way to reduce our carbon footprint and tackle rising atmospheric CO2 levels, particularly given its potential economic benefits. By utilizing the Earth’s natural seawater sink, the ocean capture system could reduce our reliance on more expensive carbon capture systems that are currently in use.
After extracting CO2 from seawater using their electrochemical system, the MIT engineers are now looking into two possible solutions: using CO2 to create fuels, chemicals, and materials, or storing it in rock formations underground. Both options are already in use for CO2 captured from the air. The team is currently in the process of patenting their ocean capture system, and they plan to couple it with existing infrastructure, such as desalination plants, at first. The end goal is to deploy their system as independent ocean capture plants worldwide. Dissolved CO2 in seawater is more than 100 times greater than in the air, making the ocean capture system a more efficient and cost-effective solution to address climate change. The original article is available on Chemistry World, and interested readers can download it along with a summary slide with questions for students.
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