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Iceland is fighting climate change by capturing CO2 and turning it into stone

Humans produced nearly 36 gigatons of carbon dioxide (CO2) emissions in 2014 and, even with advances in renewable energy, we won’t significantly decrease those emissions any time soon. Iceland’s contribution to this figure is marginal, but the island nation plays a key role in the effort against climate change. A new study on Reykjavík Energy’s CarbFix project describes an innovative way of addressing emissions by turning CO2 into stone.

Around the world, carbon capture and storage (CCS) techniques are considered one of our best bets for decreasing emissions while maintaining our current, fossil fuel-dependent energy programs. Still, most CCS techniques are expensive and potentially hazardous since they pressurize and heat the CO2 before storage, increasing its chances to leak back into the atmosphere.

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Iceland’s CarbFix project departs from the standard storage model and pumps CO2 deep underground into the country’s volcanic rock, where the gas reacts with calcium, magnesium, and iron in basalt to create solid carbonate minerals. The method was tested at the world’s largest geothermal power plant, Hellisheidi, with remarkable results. Though researchers predicted the process of turning the CO2 to stone would take hundreds or thousands of years, they were surprised to find that 95 percent of the gas was solidified in just two years.

At Hellisheidi, volcanically heated water is used to run turbines to generate energy – a process that produces 40,000 tons of CO2 each year. CarbFix has managed to store 5,000 tons of those emissions each year, with plans to increase storage to 10,000 in 2017.

Where standard CCS costs between $65 to $100 per ton of storage, CarbFix project manager Edda Aradóttir told MIT Technology Review that their method costs just $30 per ton. CarbFix also boasts that the method can be expanded to other regions with basaltic rocks, which can be found throughout the ocean floor and under 10 precent of continental land.

CarbFix isn’t free from criticism though. Some have called the 25 tons of water required to treat each ton of CO2 excessive, though CarbFix insists seawater could be used. Others have also pointed out that Iceland’s basaltic rock is more suitable for such a CCS technique than basalt in other regions. Lastly, global CO2 emissions are so immense that the CarbFix solution will likely only put a small dent in the world’s overall carbon emissions.

Nonetheless, CarbFix offers a promising alternative to other CCS techniques and one that may help reduce carbon emissions until renewable energy becomes the norm.