Geochemical reactions may decrease effectiveness of carbon storage schemes

New research shows that the natural reactions taking place in some of the underground reservoirs used to store carbon dioxide may prevent carbon emissions from being transported to greater depths, where it may be less likely to leak into the atmosphere. CO2 may not behave as expected when stored in aquifers, challenging some of our previous assumptions about CCS schemes - Silvana Cardoso Geochemical reactions taking place in aquifers - underground layers of water-bearing porous rock -may lead to carbon dioxide being 'pooled' for hundreds or even thousands of years, and may force a rethink of how these underground reservoirs are used in carbon capture and storage (CCS) schemes. The new research, from the University of Cambridge, has shown that aquifers rich in silicate minerals may delay, or even prevent, CO2 from being carried to greater depths, where it may be less likely to leak out of the aquifer and into the atmosphere. The results are published in the journal Nature . Saline aquifers have been considered the safest and most efficient option for CCS schemes, where anthropogenic carbon emissions are trapped and stored underground so that they do not enter the atmosphere. Both dissolution in the formation water and transport to depth decrease the risk of CO2 escaping: dissolution reduces the risk of potential upward leakage through fractures in the cap rock of the reservoir, while transport to greater depth increases the rate of dissolution and of potential incorporation of the CO2 into the rock minerals.