In a world first, a team of engineers and scientists at Iceland’s Hellisheidi power plant have been able to capture carbon emissions and turn them into stone for storage. This new process, described in this week’s issue of the journal Science, involves mixing carbon dioxide and hydrogen sulfide released by the plant with water, and injecting the mixture into underground layers of basalt. Within months, the mixture is converted into rock-hard carbonate, safely storing the carbon and preventing it from entering the atmosphere.
The CarbFix Project brought together scientists from Columbia University, the University of Copenhagen, the University of Iceland, and Reykjavik Energy, the operator of the plant.
Initially, scientists were concerned the process might take hundreds or thousands of years to occur naturally. Instead, large portions had mineralized into a stable form within a few months, and 95% completed the process within two years. The quick action of the process is promising — provided that a power plant is located in an area with easy access to layers of underground volcanic basalt. These conditions are perfectly suited to the seismically active landscape of Iceland, but might not work as well in other parts of the globe.
There are other challenges to implementing this process widely. For one thing, the Hellisheidi plant is a geothermal energy facility, which uses turbines to process superheated water pumped from deep underground. Not only do these types of facilities produce far less carbon than a traditional coal-fired plant (only about 5%), they also have access to vast amounts of water which can be injected back underground.
While sea water could be used to help sequester carbon in some facilities that burn fossil fuels, access to water may be a struggle in many regions. Still, there are many areas along the seafloors of the US coast where the process could easily be implemented. While the Hellisheidi plant has so far been able to process CO2 for about $30 per ton, it’s likely that a coal-fired power plant would end up spending closer to $130 per ton of carbon converted into stone.
Photos via The Earth Institute at Columbia University