Can we just turn excess carbon dioxide into rock?

SOUTHAMPTON, England, June 9 (UPI) -- A number of geological, biological and climatological processes work to sequester carbon dioxide, keeping it from being subsumed by the atmosphere and accelerating the greenhouse gas effect. Now, researchers suggest humans may have their own strategy for CO2 sequestration.

A new study conducted by a team of scientists in the United States and Europe found CO2 injected into volcanic rock becomes mineralized and permanently trapped.

Researchers have previously considered disposing of excess CO2 in abandoned underground oil and gas reservoirs, but concerns about leakage had prevented the concept from becoming reality. And until now, scientists thought the process of CO2 mineralization would take too long to be worthwhile.

The latest findings, detailed in the journal Science, prove otherwise.

"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," Juerg Matter, associate professor of geoengineering at the University of Southampton, said in a news release.

Researchers conducted their experiments in Iceland, where the bedrock is some 90 percent basaltic -- a product of the island's volcanic past -- and rich in calcium, magnesium and iron. Scientists dissolved CO2 in water and pumped it deep into the bottom of a well. Upon contact with the basaltic bedrock, the CO2 solution reacts to form carbonate minerals.

"Carbonate minerals do not leak out of the ground, thus our newly developed method results in permanent and environmentally friendly storage of CO2 emissions," Matter explained.

Researchers conducted the same experiment in several underground wells, using chemical tracers to monitor the changing composition of the CO2 solution. The tracers offered proof that the majority of CO2 was transformed into rock.

The research was supported by CarbFix, a research program funded by the European Commission and United States Department of Energy.

Scientists say their findings are proof of the potential of carbon mineralization as a climate change mitigation technology, but as always, there is more research to be done.

"The overall scale of our study was relatively small," admitted Matter. "So, the obvious next step for CarbFix is to upscale CO2 storage in basalt. This is currently happening at Reykjavik Energy's Hellisheidi geothermal power plant, where up to 5,000 tonnes of CO2 per year are captured and stored in a basaltic reservoir."