Faced with ever-growing human greenhouse gasses emissions, scientists have been working round the clock to come up with new solutions to try and trap CO2. In that context, a recent study opened the door to the possibility of basalt based carbon sequestration.
During the first and second industrial revolutions, fossil fuels served as the backbone on which industrial activity and modern transports were developed. This has resulted in an alarmingly fast increase of humanity’s carbon footprint, and today, staggering 40 billion tons of carbon dioxide (CO2) are released in the atmosphere every year.
By mining and burning fossil fuel since the beginning of the industrial revolution, humans significantly increased the amount of greenhouse gas in the atmosphere. As the effects of global warming are more and more apparent, the scientific community is slowly coming to agree that the world will fail to keep temperature increases under the 2°C limit fixed under the COP21 Agreement. Such a failure would trigger violent and irreversible changes in seasonal patterns, and force millions – if not thousands – of climate refugees on the road.
Many recent studies show that CO2 emissions will not be reduced in time, and are calling for the development of alternative solutions that would reduce carbon footprint as much as possible. One solution taken seriously is trapping CO2 underground. A recent study led by a team of researchers under the supervision of Bénédicte Ménez, from the Paris Institute of Planetary Physics, has found that basalt (a volcanic rock) would do a great job at capturing the gas.
For this study, researchers buried 230 tonnes of the gas in basaltic grounds to a depth of 400-500m. It was dissolved in water to prevent it escaping. They used tracer chemicals to show that over 95% of CO2 was turned into stone within two years. Basically, scientists have accelerated carbonate mineral formation in basaltic rocks.
This could be used to get rid of part of the CO2 in our atmosphere. The idea is that by injecting CO2 deep underground, it would precipitate. In order to get this reaction, it must be mixed with water. The resulting liquid would have a PH level of 3,2 because of the carbonic acid it contains. What happens is, this very acidity dissolves the calcium ions and magnesium of the basaltic rock before fusing with it.
Studies showed that within two years, most of the carbon would been absorbed. It would then be trapped in a solid form for thousands of years. One potential challenge for the new technique, however, is that it requires large amounts of water: 25 tonnes for each tonne of CO2 buried.