There is a global race to slow the pace of climate change to reduce the amount of harmful gases in our atmosphere, and one way to do this is through carbon capture and sequestration – absorbing and burying carbon from the air. But at this point, we’re capturing only a tiny fraction of the carbon needed to create any barriers to climate change.
Researchers from the University of Texas at Austin, in partnership with ExxonMobil, have made a new discovery that could go a long way in changing that. They found a way to foster the formation of carbon dioxide-based crystal structures that could one day store billions of tons of carbon under the ocean floor over centuries, if not forever.
“I see carbon capture as insurance for the planet,” said Vaibhav Bahadur (VB), an associate professor in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering. ACS Sustainable Chemistry and Engineering. “It’s not enough to be carbon neutral anymore, we need to be carbon negative to undo the damage done to the environment over the past few decades.”
These structures, known as hydrates, are formed by mixing carbon dioxide with water at high pressure and low temperature. Water molecules reorient themselves and act like cages that trap CO2.2nd molecules.
But the process starts very slowly – it can take hours or even days for the reaction to start. The research team found that when they added magnesium to the reaction, the hydrates formed 3,000 times faster than the fastest method in use today, in as little as one minute. This is the fastest hydrate formation rate ever documented.
“Today’s most advanced method is to use chemicals to induce the reaction,” Bahadur said. Said. “It works, but it’s slower, and these chemicals are expensive and not environmentally friendly.”
Hydrates are formed in reactors. In practice, these reactors could be placed on the ocean floor. CO using existing carbon capture technology2nd it would be plucked from the air and taken to underwater reactors where the hydrates would grow. The stability of these hydrates reduces the threat of leakage present in other carbon storage methods, such as injecting gas into abandoned gas wells.
Figuring out how to reduce carbon in the atmosphere is as big a challenge as it is on Earth right now. Still, Bahadur says there are only a few research groups in the world that look at CO2.2nd hydrates as a potential carbon storage option.
“We’re only capturing half the amount of carbon we’ll need by 2050,” Bahadur said. “This tells me there is plenty of room in the technologies bucket for more options for capturing and storing carbon.”
Bahadur has been working on hydrate research since arriving at UT Austin in 2013. This project is part of a research partnership between ExxonMobil and the Energy Institute at UT Austin.
The researchers and ExxonMobil have filed for a patent to commercialize their discovery. Next, they plan to solve their efficiency problems by increasing the amount of CO.2nd During the reaction, it is converted into hydrates and continuous hydrate production is ensured.
Bahadur led the team, which also included Filippo Mangolini, an assistant professor in the Walker Mechanical Engineering Department. Other team members are: Aritra Kar, Palash Vadiraj Acharya and Awan Bhati from the Walker Mechanical Engineering Department; Hugo Celio of the Texas Materials Institute at UT Austin; and researchers from ExxonMobil.
The challenge of capturing carbon
Aritra Kar et al., Magnesium-Assisted Rapid Nucleation of Carbon Dioxide Hydrates, ACS Sustainable Chemistry and Engineering (2021). DOI: 10.1021/acssuschemeng.1c03041
Provided by the University of Texas at Austin
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