Incorporating CO2 Into Solid Rock

Burning fossil fuels for energy releases CO2 gas into the atmosphere. Most of this CO2 stays in the atmosphere, where (as a greenhouse gas) it contributes to global warming and climate change. Some of it dissolves into the oceans, where it contributes to increased ocean acidity. These problems could be mitigated if the extra CO2 could be removed from the atmosphere somehow, but so far on one method has proven to be sufficiently cheap and effective. The most promising method so far has been to store the CO2 deep underground, in the hope that it will stay buried and not leak again to the Earth’s surface.

But now new research suggests that it may be possible to incorporate CO2 into minerals within solid rock, thereby sequestering it permanently. In a pilot study in Iceland, British researchers pumped 175 tons of CO2 into formations of basalt, a volcanic type of rock loaded with minerals that can combine readily with CO2. They found that within two years, 95% of the CO2 combined with these elements to become part of the rock itself. A larger study is underway to mineralize 10,000 tons of CO2.

One problem with this method is that so far it has only been shown to be effective in basalt. Although there are areas of basalt rock on Earth’s land surface, most of it is found on the ocean floor. At present, then, sequestering CO2 permanently in basalt may be too expensive to be the method of choice in most places. Still, if we ever finally have the will to do something about rising atmospheric CO2 levels, it’ll be nice to know that there’s a way.