‘Storing CO2 the same way Mother Nature does’

In his inaugural address, Geerlings emphasises the importance of technology that can be used to capture CO2 and to store it away from the atmosphere. Estimates indicate that we could store at least 100 years’ worth of our CO2 emissions underground. This is possible, for instance, in geological formations deep under the earth’s surface.

Mother Nature
However, Geerlings plans to investigate an alternative storage method. “I have always learned a lot from Mother Nature. On our planet we have not only the well-known biological cycle, but also an anorganic cycle which plays a role in stabilising the CO2 concentration in the atmosphere. One important part of the cycle consists of an erosion reaction between commonly occurring rocks and CO2 in the air”, he explains.
CO2 dissolves in water and forms carbonic acid. The carbonic acid then reacts with alkaline rocks such as olivine, a magnesium silicate. Part of the reaction process is driven by magnesium bicarbonate ions dissolved in water. The CO2 is stored in the dissolved bicarbonate and is thus removed from the atmosphere for tens of thousands of years.
Nature is thus able to capture CO2 from the atmosphere and to store it in just one step, known as CO2 mineralisation. In principle a very large quantity of CO2 can be stored in this way. The problem, however, is that the reaction takes place extremely slowly. As Geerlings explains, “This means we will need to accelerate the reaction drastically. This can be done by grinding the required rock to a powder in order to increase the reaction surface. Moreover, it appears that one often requires a pure flow of CO2 – which is tricky, because it implies a separate energy-consuming CO2 capture stage, and that’s exactly what we wanted to do away with.”
Geerlings will thus focus on the mineralisation of diluted CO2 flows, or in other words industrial flue gases. “The question to be studied is under what conditions suitable minerals can be transformed to a state which allows diluted CO2 flows to be converted at an acceptable speed. If this research is successful then it will lead to an alternative CO2 capture and storage process that can be applied parallel to geological storage deep underground.”

Materials
A second point made by Geerlings in his inaugural speech is the importance of new and improved materials: “Energy research is, to an important extent, materials research.”
According to the professor, in the coming years we can expect a great deal from new materials that will enable the harvesting of sunlight in the form of electricity and hydrogen. In addition, new materials will become available for the efficient storage of these energy carriers. But many other new materials are needed as well, in order to enable such things as improved catalysts, membranes and absorbents.

More information
Prof. J.J.C. Geerlings, Faculty of Applied Sciences, J.J.C.Geerlings@tudelft.nl, + 31 15 27 82615

Science Information Officer Roy Meijer, +31 15 2781751, r.e.t.meijer@tudelft.nl