Carbon is released when we burn fossil fuels—fuels that began as plants extracting carbon dioxide from the air.
It’s called the Carbon Cycle. Plants thrive on carbon dioxide and sunlight. As they die and return to the earth from which they grew, the extracted carbon remains. Over millions of years the stored carbon becomes coal, oil and natural gas.
Now, man is releasing that stored carbon back to where it started, the atmosphere, wrapping the Earth in a warming blanket and choking the seas that attempt to store it.
Scientists looking for a way to return atmospheric carbon to the earth for storage have turned carbon dioxide into stone in a matter of months by pumping it deep underground, offering a revolutionary new way of storing the greenhouse gas to tackle climate change.
The pioneering experiment in Iceland mixed CO2 emissions with water and pumped it hundreds of meters (feet) underground into volcanic basalt rock — where it rapidly turned into a solid.
“We need to deal with rising carbon emissions. This is the ultimate permanent storage — turn them back to stone,” said Juerg Matter, lead author of the study, which was published Thursday in the journal Science.
Carbon dioxide is a key factor in global warming, and experts have long called for innovative “carbon capture and storage” (CCS) solutions.
Previous attempts to inject CO2 into sandstone soils or deep saline aquifers have struggled, as they relied on capping rocks to hold the gas down — triggering fears it could eventually leak.
In contrast, the CarbFix project at Iceland’s Hellisheidi plant — the world’s largest geothermal facility, which powers Reykjavik — sought to solidify the CO2.
The plant produces 40,000 tons of CO2 a year — just five per cent of the emissions of a similarly sized coal plant, but still significant. In 2012, they began pumping 250 tons of CO2 mixed with water underground.
Scientists had feared it could take hundreds or even thousands of years for the mildly acidic liquid to solidify.
But 95 per cent of the injected mixture — which they had tagged with tracer chemicals in order to check it didn’t leak out — had became chalky white stone within two years.
“It was a very welcome surprise,” said Edda Aradottir, who heads the project for Reykjavik Energy.
Encouraged by the success, the company has scaled up the project and from this summer will be burying some 10,000 tons of CO2 each year, Aradottir said.