2016-06-10. Underground injections turn carbon dioxide to stone.

posted Jun 15, 2016, 3:53 PM by Alan Gould
By Eli Kintisch, Science. For GSS Energy Use chapter 4 and Climate Change chapter 10. Excerpt: Researchers working in Iceland say they have discovered a new way to trap the greenhouse gas carbon dioxide (CO2) deep underground: by changing it into rock. Results published this week in Science show that injecting CO2 into volcanic rocks triggers a reaction that rapidly forms new carbonate minerals—potentially locking up the gas forever. The technique has to clear some high hurdles to become commercially viable. ...unlike sandstone, the basalt contains metals that react with CO2, forming carbonate minerals such as calcite—a process known as carbonation. But they thought the process might take many years. To find out, they launched the CarbFix experiment 25 kilometers east of Reykjavik, intending to dose Iceland’s abundant underground basalt with CO2 that bubbles from cooling magma underground and is collected at a nearby geothermal power plant. In 2012, the researchers injected 220 tons of CO2—spiked with heavy carbon for monitoring—into layers of basalt between 400 and 800 meters below the surface. ...What happened next startled the team. After about a year and a half, the pump inside a monitoring well kept breaking down. Frustrated, engineers hauled up the pump and found that it was coated with white and green scale. Tests identified it as calcite, bearing the heavy carbon tracer that marked it as a product of carbonation. Measurements of dissolved carbon in the groundwater suggested that more than 95% of the injected carbon had already been converted into calcite and other minerals. ... http://www.sciencemag.org/news/2016/06/underground-injections-turn-carbon-dioxide-stone