One approach to dispose of the greenhouse gas CO2 is to inject it into deep, porous geological formations, where is remains safely trapped over periods of many millennia. This report evaluates the potential for this option within Switzerland, based on a literature review.
Only geological criteria for CO2 sequestration are taken into account, following international best-practice principles for reservoir safety. Simultaneous consideration of nine geological attributes (including faulting and natural seismicity) allows the sequestration potential to be mapped at a resolution of a few km2, using a scale between 0 (negligible potential) and 1 (high potential).
It is concluded that the crystalline rocks of the Alps and the sediments underlying the valleys of Valais, Ticino and Grisons are unsuitable for CO2 sequestration. However, the sedimentary rocks below the Central Plateau (and to lesser extent below the Jura Chain), locally show moderate to very good potential. At least four formations of porous sandstones and limestones (saline aquifers) underlie large areas of the Plateau within the technically favoured depth interval of 800–2500 m. Approximately 5000 km2 of the Plateau (mostly in the sector Fribourg–Olten–Luzern) exhibits sequestration potentials above 0.6, offering a theoretical (unproven) storage capacity for approximately 2680 million tonnes of CO2.
From a purely geological point of view these results are promising. Although the high potentials do not guarantee the feasibility of CO2 sequestration, they serve as guides to areas that warrant detailed investigation. If this CO2 storage option is pursued in Switzerland, then more detailed geological investigations and a pilot study would be necessary to prove its feasibility. The assessed risks, leakage-monitoring procedures and non-geological criteria (proximity to CO2 point-sources, economics, conflicts of use of the subsurface, etc.) would have to be taken into account.
Source: Authors: Prof. Dr. Larryn W. Diamond , Institut für Geologie, Universität Bern Dr. Werner Leu , Geoform AG Gabriel Chevalier , Institut für Geologie, Universität Bern Studie im Auftrag des Bundesamtes für Energie BFE
BFE-Bereichsleiter: Gunter Siddiqi
BFE-Programmleiter: Peter Jansohn
BFE-Vertragsnummer: SI/500325-01 und SI/500386-02