MIT researchers have proposed a different approach to reducing carbon emissions and that is by directly capturing carbon from seawater, which they claim may potentially result in overall net negative emissions.
Reversible Procedure
The MIT researchers claim to have discovered the secret to a truly effective and affordable carbon removal process even though such an approach is still in its infancy.
The team created a reversible procedure using electrochemical cells without a membrane. To drive the release of the dissolved carbon dioxide from the water, reactive electrodes are utilized to release protons into the saltwater that is fed to the cells.
The procedure is cyclical: first, the water is made acidic to dissolve the inorganic bicarbonates and turn them into molecular carbon dioxide, which is then gathered as a gas under a vacuum.
To recover the protons and convert the acidic water back to alkaline before returning it to the sea, the water is then injected into a second set of cells with a reversed voltage.
When one set of electrodes has undergone a protons depletion and the other has had a regeneration during alkalization, the roles of the two cells are periodically reversed.
According to Kripa Varanasi, an MIT professor of mechanical engineering, this carbon dioxide removal and reinjection of alkaline water could gradually begin to reverse, at least locally, the acidification of the oceans.
To prevent a local alkalinity rise that can disturb ecosystems, the team suggested reinjecting alkaline water through scattered outlets or far offshore.
Similar to previous carbon removal procedures, once the carbon dioxide has been taken out of the water, it still needs to be disposed of.
Scalable System
The system might also be used in places like aquaculture farms or offshore drilling platforms. It might eventually result in the deployment of independent carbon removal facilities all over the world.
"This system is scalable so that we could integrate it potentially into existing processes that are already processing ocean water or in contact with ocean water," Varanasi said in a statement.
The goal of the ongoing research is to develop a replacement for the current carbon removal procedure, which involves removing the separated carbon dioxide from the water using a vacuum.
Additionally, the team must come up with operational tactics to stop the precipitation of minerals that could clog the alkalinization cell's electrodes, a recurring problem that lowers the effectiveness of all previously reported methods.
The team anticipates that the system will be prepared for a real-world demonstration project within two years.
The findings of the study were published in journal Energy and Environmental Science.
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