There is a global race to reduce the number of harmful gases in our atmosphere in order to slow the rate of climate change, and one method is carbon capture and sequestration, which involves sucking carbon out of the air and burying it. At the moment, however, we’re only capturing a fraction of the carbon needed to make a dent in climate change.
Researchers have discovered a way to boost the formation of carbon dioxide-based crystal structures, which could someday store billions of tons of carbon beneath the ocean floor for centuries, if not forever.
Researchers from The University of Texas at Austin, in collaboration with ExxonMobil, have made a new discovery that could help change that. They’ve discovered a way to speed up the formation of carbon dioxide-based crystal structures, which could someday store billions of tons of carbon beneath the ocean floor for centuries, if not forever.
Researchers have found a way to supercharge the formation of carbon dioxide-based crystal structures that could someday store billions of tons of carbon under the ocean floor for centuries, if not forever.
“I see carbon capture as insurance for the planet,” said Vaibhav Bahadur (VB), an associate professor in the Walker Department of Mechanical Engineering at the Cockrell School of Engineering and the lead author of a new paper on the research published in ACS Sustainable Chemistry & 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 last several decades.”
When carbon dioxide is mixed with water at high pressure and low temperature, these structures, known as hydrates, form. Water molecules reorient and act as cages, trapping CO2 molecules. However, the process is very slow to begin; it can take hours or even days to get the reaction started. The researchers discovered that by adding magnesium to the reaction, hydrates formed 3,000 times faster than the fastest method currently in use, in as little as one minute. This is the fastest rate of hydrate formation ever recorded.
“The most advanced method today is to use chemicals to promote the reaction,” Bahadur explained. “It works, but it takes longer, and these chemicals are expensive and harmful to the environment.”
Hydrates are formed in reactors. These reactors could be placed on the ocean floor in practice. CO2 would be extracted from the atmosphere and transported to underwater reactors where hydrates would grow using existing carbon capture technology. The stability of these hydrates reduces the risk of leaks in other carbon storage methods, such as injecting it as a gas into abandoned gas wells.
Trying to figure out how to reduce carbon in the atmosphere is about as big a problem as the world has right now. Despite this, only a few research groups around the world are looking into CO2 hydrates as a potential carbon storage option, according to Bahadur.
“We’re only capturing about half of the carbon that we’ll need to capture by 2050,” Bahadur said. “This tells me that there is plenty of room for more options in the bucket of carbon capture and storage technologies.” Since his arrival at UT Austin in 2013, Bahadur has been working on hydrate research. ExxonMobil and the Energy Institute at UT Austin collaborated on this project as part of research collaboration.
To commercialize their discovery, the researchers and ExxonMobil have filed a patent application. Next, they intend to address efficiency issues, such as increasing the amount of CO2 converted into hydrates during the reaction and establishing continuous hydrate production.
Under high pressure and low temperature, CO2 and water trapped in the sediment beneath the seafloor crystallize into hydrate, stable ice. The big assumption, as with most underground CO2 storage scenarios, is that the Earth’s living geology will do whatever it wants over centuries and millennia. Fractures in the sub-sea sediment, either pre-existing or caused by tectonics or CO2 injection, could open a pathway for CO2 to escape—though there is still considerable uncertainty.
