Method of supercharging metals to bury billions of tons of harmful carbon dioxide under the sea for centuries

  • Carbon capture and burial is one of the most promising ways to slow the pace of climate change
  • Researchers at the University of Texas and ExxonMobil have found a way to speed up the formation of crystal structures called hydrates that can store billions of tons of carbon for centuries
  • Adding magnesium to the reaction resulted in a 3000-fold increase in the waiting time for hydrate formation, from hours or even days to minutes.

There is a global race to reduce the amount of harmful gases in our atmosphere in order to slow the rate of climate change, and one way to do that is to capture and sequester carbon – by sucking carbon out of the air and making it happen. burying it. At this point, however, we are only capturing a fraction of the carbon needed to reduce climate change.

Researchers at the University of Texas at Austin, in partnership with ExxonMobil, have made a new discovery that could greatly change that. They found a way to supercharge the formation of carbon dioxide-based crystal structures that could one day store billions of tons of carbon below the ocean floor for centuries, if not forever.

“I see carbon capture as insurance for the planet,” said Vaibhav Bahadur (VB), associate professor in the department of mechanical engineering at the Cockrell School of Engineering and lead author of a new paper on research in ACS Sustainable Chemistry and Engineering. “It is no longer enough to be carbon neutral, we have to be carbon negative to repair the damage done to the environment in recent decades. “

These structures, called hydrates, form when carbon dioxide is mixed with water at high pressure and low temperature. The water molecules reorient themselves and act like cages that trap the CO2 molecules.

But the process starts very slowly – it can take hours or even days for the reaction to start. The research team found that by adding magnesium to the reaction, hydrates formed 3,000 times faster than the fastest method used today, in just one minute. This is the fastest rate of hydrate formation ever documented.

“The advanced method today is to use chemicals to promote the reaction,” Bahadur said. “It works, but it’s slower, and these chemicals are expensive and unfriendly to the environment.”

Hydrates are formed in reactors. In practice, these reactors could be deployed at the bottom of the ocean. Using existing carbon capture technology, CO2 would be extracted from the air and channeled to submarine reactors where hydrates would develop. The stability of these hydrates reduces the threat of leakage present in other methods of carbon storage, such as injecting it as a gas into abandoned gas wells.

Figuring out how to reduce carbon in the atmosphere is about as big a problem as there is in the world right now. And yet, says Bahadur, only a few research groups in the world are studying CO2 hydrates as a potential carbon storage option.

“We are only capturing about half of one percent of the amount of carbon we will need by 2050,” Bahadur said. “That tells me there is a lot of room for more options in the bucket of technologies to capture and store carbon.”

Bahadur has been working on hydrate research since joining 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 applied for a patent to commercialize their discovery. Next, they plan to tackle efficiency issues – by increasing the amount of CO2 converted to hydrates during the reaction – and establishing continuous hydrate production.

Reference: “Magnesium-Promoted Rapid Nucleation of Carbon Dioxide Hydrates” by Aritra Kar, Palash Vadiraj Acharya, Awan Bhati, Ashish Mhadeshwar, Pradeep Venkataraman, Timothy A. Barckholtz, Hugo Celio, Filippo Mangolini and Vaibhav Bahadur, August 11, 2021, ACS Sustainable Chemistry and Engineering.
DOI: 10.1021 / acssuschemeng.1c03041

The research was funded by ExxonMobil and a grant from the National Science Foundation. Bahadur led the team, which also includes Filippo Mangolini, assistant professor in Walker’s Mechanical Engineering Department. Other team members include: from Walker’s Mechanical Engineering Department, Aritra Kar, Palash Vadiraj Acharya and Awan Bhati; from Texas Materials Institute at UT Austin Hugo Celio and researchers from ExxonMobil.


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