Scientists say they may have found a radical breakthrough to tackling climate change – by pumping heat-trapping carbon dioxide into the ground and turning it into stone.
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The process was tested in an experiment in which the team pumped a mixture of Carbon dioxide and water underground into volcanic rock. “This is the ultimate permanent storage-turn them back to stone”, said lead author Juerg Matter, an adjunct researcher at Lamont now based at the United Kingdom’s University of Southampton, in a press release.
“Carbonate minerals do not leak out of the ground, thus our newly developed method results in permanent and environmentally friendly storage of Carbon dioxide emissions”, he added.
The team is already ramping up the carbon capture method at Reykjavik Energy’s Hellisheidi geothermal power plant, where the original study took place.
Under a pilot project called Carbfix, started in 2012, the plant began mixing the gases with the water pumped from below and reinjecting the solution into the volcanic basalt below. They feared it could take hundreds or even thousands of years for the mildly acidic liquid to solidify.
On Thursday, the company announced that it has succeeded, reporting that 95 percent of the carbon stored underground at the Hellisheiði power plant, near Reykjavík, has mineralized less than two years after being injected into the earth. The reaction between the basalt rocks and gas formed carbonate, a material similar to limestone, which can’t leak back out into the environment. There were various proposals for storing Carbon dioxide in old oil wells, empty underground aquifers, and unminable coal seams.
The team initially piped 227 tonnes of Carbon dioxide mixed with water and hydrogen sulphide to a depth of 400 to 800m. Chosen sites – which have included disused oil and gas wells – have relied on layers of impermeable capping rocks to hold down the carbon dioxide.
Together with Reykjavik Energy, the research team designed an experiment around the Hellisheidi geothermal power plant.
These typically involved pumping pure carbon dioxide into sandstone, or deep, salty aquifers, then sealing the carbon basins with caprock. Dubbed the CarbFix project, the researchers have happened upon a method of stowing carbon away that could seriosuly fast-track the mineralization process.
“We were surprised”, said study co-author Martin Stute, a hydrologist at Columbia University in NY. With an abundance of basalt and water aplenty, the plant has the ideal conditions for the carbon capture process to take place.
The approach announced this week aims to reduce this risk by dissolving Carbon dioxide with water and pumping the mixture into volcanic rocks called basalts.
Compared with previous attempts at carbon capture, the surrounding basalt contained plenty of calcium, iron and magnesium, and water was also pumped down with the CO2, which had not been done before.
Researchers tested this theory by core drilling the test area, where they got rock samples with hints of white carbonates.
As per the scientists the method would be ideal for fossil-fuel plants, but it still needs to overcome some hurdles. And since basaltic rock is found on 10 percent of continental land and all across the ocean floor, there is more than enough room for this technology to expand.
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While much of this happened underground, the researchers also saw fine crystals of carbonate sticking to the surface of the pump and pipes at the monitoring well.
