Of known planet-warming greenhouse gases, carbon dioxide is of particular concern because it is emitted through human activities.
In 2014, for instance, carbon dioxide made up more than 80 percent of the United States' anthropogenic greenhouse gas emissions largely from power plants, vehicles and industries.
Researchers, however, appeared to have inched closer to finding a way to solve the problem of carbon emissions. Engineers and scientists who work at an Iceland power plant have shown that carbon dioxide emissions can be injected into the Earth and chemically changed into a rock.
The process, which turned out radically faster than thought, may help address concerns plaguing other methods of so-called carbon capture and sequestration, or CCS, to capture waste carbon dioxide.
One problem with capturing and storing carbon dioxide underground, for instance, is that this may possibly result in the emissions seeping back into the air or even exploding out.
In a paper published in the journal Science, researchers described the success of a method through which carbon emissions are instead trapped to no longer pose an environmental threat.
The study, which is part of the CarbFix Project, took place in Iceland's Hellisheidi power plant, the largest geothermal facility in the world. The plant generates electricity by pumping up volcanically-heated water to run turbines, but it also brings up volcanic gases that include carbon dioxide.
Researchers dissolved carbon in water to prevent it from escaping and then injected it into wells that pass through basaltic lavas and formations 400 to 800 meters below the ground. The reaction between the basalt rocks and gas formed carbonate, a material similar to limestone, which can't leak back out into the environment.
"Carbonate minerals do not leak out of the ground, thus our newly developed method results in permanent and environmentally friendly storage of CO2 emissions," said study author Juerg Matter from the University of Southampton.
The method also appears efficient and fast. More than 95 percent of the carbon dioxide was turned into stone. The researchers' most optimistic estimate is that it would take between eight to 12 years before carbon could solidify into stone, but 250 tons of carbon were turned into carbonate within a period of just two years.
"We find that over 95 percent of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than two years," the researchers wrote in their study.
"Our results, therefore, demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated."
