Brussels - Capturing CO2 from power stations and storing it underground is considered by many to be a feasible way of reducing carbon emissions, allowing society more time to replace fossil fuels with renewable and sustainable sources of energy. As part of ongoing experiments into the effectiveness and safety of storing carbon dioxide underground, the researchers injected CO2 into samples of sandstone rocks taken from the German Stuttgart Formation, a potential area of long-term storage for CO2. Here, the first European on-shore storage site of CO2, partly funded by the EU under the CO2 SINK project, can be found at Ketzin.
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The series of experiments provided information on the long-term behaviour of the CO2 stored in the rocks. The rock samples were placed in high-pressure containers and exposed to CO2 for varying lengths of time, under similar temperature and pressure conditions to those found in the actual storage site. The brine used in the experiments was similar to that found in the sandstone reservoirs at Ketzin.
After six months of exposure there were no significant changes in the rocks. After 15 months, it appeared that the rocks were becoming slightly more porous and absorbent as there were a higher proportion of larger-sized pores. These small changes could result from minerals in the rock dissolving, which would enlarge the pores, and it is not believed that this could be an issue for carbon storage in sandstone aquifers.
Longer-run exposure experiments are continuing and no further relevant changes have been observed in the rocks. Results to date from a wide range of experiments suggest that long-term storage of CO2 in the German Stuttgart Formation is feasible.
Original source: Zemke, K., Liebscher, A., Wandrey, M. et al. (2010) Petrophysical analysis to investigate the effects of carbon dioxide storage in a subsurface saline aquifer at Ketzin, Germany (CO2SINK). International Journal of Greenhouse Gas Control. Doi:10.1016/j.ijggc.2010.04.008. Quelle: EU commission