Experts transform CO2 ‘into stone’

According to the researchers, the method might help allay fears that stored CO2 emissions could seep back into the atmosphere or explode.

We need to deal with rising carbon emissions. This is the ultimate permanent storage — turn them back to stone

Lead author Juerg Matter

To develop the process, the research team began mixing CO2, volcanic gases and hydrogen sulphide with water before reinjecting the solution with basalt taken from beneath the plant.

Because of the basalt’s composition, 95% of the stored CO2 was converted to a solid within two years, which is much faster than previously predicted, the researchers said.

“This means that we can pump down large amounts of CO2 and store it in a very safe way over a very short period of time,” said study co-author Martin Stute, a hydrologist at Columbia University's Lamont-Doherty Earth Observatory.

“In the future, we could think of using this for power plants in places where there's a lot of basalt — and there are many such places,” Stute added.

However, power plants would also need a large amount of water to conduct the process effectively, the researchers said.

Plants would need roughly 25 tonnes of water for every tonne of CO2 they wanted to solidify, said Sigurdur Gislason, a University of Iceland geologist and study co-author.

He added that fossil fuel plants without an abundant water supply would also likely not be able to use the process at all.

But despite the potential pitfalls, lead author Juerg Matter said: “We need to deal with rising carbon emissions. This is the ultimate permanent storage — turn them back to stone.”

A full account of the research has been published in the journal Science.