Sequestering CO₂

Even with the current trend toward renewables and energy efficiency, carbon capture and sequestration (CCS) remains an essential component of a globally sustainable energy future, as increasing CO₂ levels in the atmosphere contribute to growing concerns regarding climate change and ocean acidification. CCS refers to the process of removing carbon dioxide (the by-product of fossil-fuel power plants) from smokestacks and pumping it into rock formations deep underground. One of the main problems with this approach is that storage sites require monitoring (for decades or even longer) to ensure that gasses don’t escape back into the atmosphere. But scientists recently came up with a way to store CO₂ while drastically reducing the need for long-term monitoring. The key was finding the right rock.

Volcanic rocks – also known as basalts – contain large concentrations of calcium, magnesium and iron, all of which react readily with carbon dioxide to form a solid mineral called calcite. The process essentially turns the gas into stone, locking it away permanently. It was tested at a geothermal utility plant in Iceland where researchers pumped 250 tons of CO₂ mixed with water into porous basalt about 1,500 feet below the surface. The gas was laced with a radioactive isotope so that it could be traced as it spread through the rock. In less than two years, they found that approximately 95 percent of the CO₂ had been converted into calcite.

The researchers believe that this process could be used to store billions of tons of carbon dioxide each year enabling significant reductions in global CO₂ emissions, at least until alternative technologies can replace fossil fuels as our primary sources of energy.