Applicability of Noble Gases for CO2 Capture and Storage Monitoring

Carbon capture and storage is a climate change mitigation technology that can help limit global warming. Monitoring strategies are put into place to inform on the fate of the injected CO2. Noble gases can play an important role in such strategies. By applying recently developed noble gas measurement technology, modelling and an injection experiment, this thesis advances the understanding of CO2-noble gas systems. Noble gas concentrations in captured CO2 are found to vary significantly at capture plants and repeated sampling is needed to describe the noble gas content holistically. At all plants, the CO2 has low noble gas concentrations; therefore, injected CO2 will take up noble gases from the pore water of a storage reservoir. This uptake alters the noble gas concentrations so dramatically that leakages into the atmosphere or natural gas reservoirs become identifiable. The injection experiment confirms the exchange with the pore-water and confirms that noble gases, in contrast to CO2, behave conservatively. Consequently, noble gases have an early warning function, which can be utilized by adding noble gases to the injected CO2. However, this is currently uneconomical.