After opening the world's first commercial Direct Air Capture (DAC) plant designed to pull CO2 out of the air, Swiss company Climeworks is now joining forces with a geothermal power plant in Iceland to create the world's first "negative emission" power plant.

For several years an international team of scientists has been working on a novel way to turn captured CO2 into solid minerals. The project is dubbed CarbFix and involves bounding the CO2 to water and then pumping it 700 meters (2,300 ft) underground. This CO2 solution, on contact with the deep basalt rock, was found to quickly form into a carbonate mineral.

Before this discovery it was thought that this mineralization process could take anywhere from hundreds to thousands of years, but the CarbFix team were surprised to discover the CO2 formed into a solid mineral in under two years.

"Our results show that between 95 and 98 per cent of the injected CO2 was mineralized over the period of less than two years, which is amazingly fast," says lead author on the CarbFix project, Dr Juerg Matter.

Climeworks has been pioneering a novel DAC system over the past few years. The technology can collect CO2 from ambient air onto a patented filter before it is purified and then sold on to businesses needing the gas in a commercial context. The first commercial plant in Zurich is delivering the collected CO2 to a nearby greenhouse.

Carbon sequestration, where CO2 is captured and stored in underground reservoirs, has been the source of much controversy in recent years. An MIT study from 2015 suggested that prior sequestration processes have not been especially effective. So while we can capture the CO2 we still don't have a large-scale method to safely dispose of it, and there is a very real concern that sequestered CO2 could leak back into the atmosphere.

Combining the Climeworks DAC technology with the CarbFix mineralization process offers a proof-of-concept for a system that is not only carbon neutral but actually carbon negative.

"The potential of scaling-up our technology in combination with CO2 storage, is enormous," says Climeworks CEO Christoph Gebald. "Not only here in Iceland but also in numerous other regions which have similar rock formations."

Of course the economic cost of deploying this kind of carbon capture technology on a large scale is not particularly pragmatic right now, but for the first time we are seeing realistic and effective carbon capture and storage systems.

Source: Climeworks

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