A team of international research scientists is pioneering a new and promising way to capture and store carbon dioxide, the potentially harmful greenhouse gas: Turn it into stone.
Researchers on the CarbFix project began testing that idea in Iceland in 2014 by injecting atmospheric CO2 deep into volcanic basalt rock formations. The results surprised and encouraged the scientists. Within two years, nearly 250 tons of CO2 was transformed into carbonate crystals.
“Our results show that between 95 and 98 percent of the injected CO2 was mineralized” — and “amazingly fast,” said project report lead author Juerg Matter, of the University of Southampton, U.K.
The large Hellisheidi geothermal power station in Hengill, Iceland, supplied the CO2 emissions for the pilot project. The experiment ended, but the power plant continues the work, with plans to inject 10,000 tons of CO2 this summer, according to Columbia University environmental scientist and research team member Martin Stute. The goal is to eventually capture the power station’s total CO2 emissions of 40,000 tons in stone.
“So far they haven’t encountered any trouble,” Stute said, “so that is a good sign.”
It could be an important breakthrough, because carbon dioxide from human activity is a chief accelerant of climate change. Tons of it spew daily from coal, oil and natural gas refineries and from motor vehicle exhaust pipes.
There is no shortage of places where you can put CO2, Stute said, citing one example in Oman: “That one rock formation in Oman could take all human CO2 emissions for hundreds of years.”
Basalt rock formations occur throughout the world, even under the ocean floor. Brazil, India, South Africa and the United States possess huge expanses of basalt.
And that suggests another futuristic strategy: Rather than capturing CO2 from power plants alone, remove the gas from the air anywhere. “There are lots of promising laboratory and field results,” Stute said.
CO2 can be captured anywhere, because it’s in the air in similar concentrations worldwide. If captured near volcanic rock and water, the CO2 could be injected and mineralized on the spot — cost-effectively.
Getting the price down
Grabbing CO2 from the air where basalt and water resources are plentiful is, at $20 to $30 per ton, relatively economical. Capturing and transporting carbon can cost five times as much, or even more, depending on the how far the carbon must be moved.
Another cost factor is how the carbon is generated. The gases emitted at the Iceland geothermal plant were mostly CO2 and hydrogen sulfide. Fossil fuel plants produce more gases that must be separated from the CO2.
Do it now
CarbFix project scientists agree that carbon capture and storage could help bridge the gap while efficient renewable energy technologies are more widely adopted.
But they say renewables alone won’t be enough to offset the detrimental effects of greenhouse gas emissions. “We cannot get rid of fossil fuel that rapidly,” Stute said. If global temperature rise is to be kept well below 2 degrees Celsius above pre-industrial levels, now is the time to employ every means available.
It comes down to economics, he added: “There has to be incentive to do something about CO2 emissions. … If the incentive is there it can be done. We need to take it seriously.”
The CarbFix project is funded by the U.S. Department of Energy and the European Union and includes scientists from Australia, Britain, Denmark, France, Iceland, the Netherlands and the U.S.