Anthropogenic emissions of CO2 into the atmosphere are thought to increase global warming and hence climate change. One approach to avoid these emissions is to capture CO2 at the site of its production (e.g. fossil-fuel power plants, cement and chemical factories), then inject it into deep porous rock formations. Suitable formations for this technology are those that resemble natural gas reservoirs, in which impermeable caprocks have sealed in the gas for many millions of years.
We are evaluating the potential for permanent, safe sequestration of CO2 in deep saline aquifers in the subsurface of Switzerland, for two reasons. First, it could provide an option to reduce present-day CO2 emission rates. Second, it could enable CO2-neutral operation of gas-fired power stations, should they be required as an interim source of electricity in the future. It is expected that Switzerland will phase-out its nuclear power stations by 2050, but it is uncertain whether renewable energy sources will be able to fill the ensuing gap in electricity supply by that date. Gas-fired power stations could be acceptable only if a local means is available to sequester the CO2 produced by burning methane. Thus, knowledge of the feasibility of large-scale CO2 sequestration within Swiss territory is important for energy planning.
Given this geo-energy context, our research is being funded by the on-going National Research Project 70 "Energy Turnaround", administered by the Swiss Science Foundation (SNF). We are conducting this research as members of the Swiss Competence Center for Energy Research – Supply of Electricity (SCCER–SoE), financed by the Federal Commission for Technology and Innovation (CTI).
We have evaluated the potential for CO2 sequestration in Switzerland based on geological data in the literature.
Our literature study (Chevalier et al., 2010[LD1] ) identified several major saline aquifers within the sedimentary rocks of the Swiss Molasse Basin. We are now investigating in detail the gas-storage and geothermal properties of the largest of these, the "Upper Muschelkalk" carbonate aquifer.
We use numerical modelling to simulate injection of CO2 into the subsurface. The simulations help predict the fate of CO2 as it migrates through the reservoir and interacts with porewaters and reservoir rocks. This aids in site-selection, in estimating the storage capacity and injection rates of given sites, and in designing long-term surveillance programmes.