In the not too distant future we’re probably going to have to remove carbon dioxide from the atmosphere, to address the climate emergency. Most carbon capture and storage methods involve injecting gaseous or dissolved carbon dioxide into underground reservoirs, but there is always a niggling worry that it could leak out again. The alternative is carbon mineralisation: a chemical reaction where the carbon from carbon dioxide is locked into a mineral.
Carbon mineralisation happens naturally during rock weathering and stores carbon safely for thousands of years, but until now its potential was thought to be limited because mineralisation clogs up the pores in a rock, blocking entry and preventing further reactions. However, recent experiments indicate that in some rocks (such as olivine) the crystals created during the process of mineralisation expand the rock and force new cracks to appear, which create fresh surfaces and enhance the rock’s carbon storage capacity.
The results, which were presented at a meeting of the American Geophysical Union in December 2021, showed that some rocks carried on absorbing carbon for more than a month.
“Now we’re hoping to find a way to optimise this process so we can help implement more pilot projects around the world,” says Catalina Sanchez-Roa, from Columbia University Climate School in New York.