Hydrates allow the storage of CO2 captured on the ocean floor
The recourse to CO2 capture as a feasible solution must not depend solely on technological development to increase the absorption capacity. Another crucial aspect is the storage of CO2 captured from the air or the sea. And if there has been growing interest on the front in recent years – with some progress, albeit limited, you can see Climeworks’ latest DAC plants – the second front has a slower rate of innovation.
A group of researchers from the University of Austin, Texas, focused on precisely how to make the processes that allow the storage of captured CO2 more efficient. They developed a system six times faster than current ones, reliable in terms of durability, and without recourse to chemical solvents.
The most widespread method today is the injection of CO2 in a gas-like state into geological deposits. Typically, the choice falls on deposits exhausted from gas and oil. However, it also applies to those in danger of depletion, with the pumping of CO2 that allows the extraction of additional amounts of hydrocarbons. This model has many margins of uncertainty, both in terms of the speed at which the CO2 captured can be stored and the actual duration of the storage.
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The “plan B” is to convert the CO2 captured into carbon dioxide hydrates, a solid compound that guarantees greater durability over time and greater ease in finding adequate deposits. However, because of its high energy intensity, this process is slow and expensive.
Magnesium accelerates the storage of captured CO2
Researchers at the University of Austin have developed a process that is up to six times faster and less expensive to make the storage of captured CO2 “more accessible and feasible on a global scale.” How? By replacing the chemical solvents commonly used as catalysts of the hydrate formation process with magnesium and applying the method of capturing CO2 from seawater.
“This technology works well with seawater, which makes it easier to implement because it does not rely on complex desalination processes to create fresh water,” the authors explain. “Hydrates are interesting options for carbon storage as the seabed offers stable thermodynamic conditions, which protect them from decomposition.”