Storing CO2 underground as part of a climate strategy "sensible and feasible"

In a joint position paper, the Federation of German Industries (BDI), the Confederation of German Trade Unions (DGB) and the environmental associations Naturschutzbund Deutschland (NABU) and World Wide Fund For Nature (WWF) have come out in favor of storing CO2 underground (carbon capture and storage, CCS) as part of a comprehensive climate strategy. Such technical solutions should - in addition to strengthening intact ecosystems as natural carbon sinks - also be used in Germany.

"As a geologist, I welcome the joint position of the associations on CCS technologies. I consider their implementation to be sensible and feasible," says Professor Christoph Hilgers from the Institute for Applied Geosciences (AGW) at KIT. "There are many industrial processes in which CO2 cannot be avoided - such as cement production. The CO2 can be separated using technical processes and injected underground via a transport infrastructure. There it can be stored permanently." The technical feasibility was already successfully demonstrated in the USA in the 1970s. CCS is already in practical use in Norway, where around one million tons of CO2 are stored underground every year.

In Germany, on the other hand, there is still a de facto ban on the technology. "The moratorium is not scientifically well-founded," argues Hilgers. "In principle, we have large volumes of rock in Germany in which it is possible to store CO2 in the long term. The CO2 is liquefied by pressure and stored at a depth of around one kilometer. There it then behaves like a liquid and tends to remain underground. The Federal Institute for Geosciences and Natural Resources has already comprehensively investigated where CCS is safely possible at the beginning of the millennium."

Of course, possible risks must be kept in mind, Hilgers emphasizes, for example that CO2 could return to the surface through old boreholes or that in certain geological constellations CO2 could also escape naturally due to excess pressure underground. "This possibility must of course be comprehensively investigated before a storage site is released. Then I consider the risk to be manageable and limited. After weighing up the opportunities and risks, I consider CCS to be indispensable for achieving our climate targets."