The UK has challenging green house gas (GHG) reduction targets. It is believed that carbon capture and storage (CCS) will play a critical role in the energy systems of the future, in part to support the decarbonisation objective and in part to provide grid flexibility in a future system including a large fraction of less responsive low carbon energy systems (e.g. nuclear baseload and intermittent wind). The proposed research methodology is based on multiscale modelling. This involves the development of fit-for-purpose models of the individual components which describe phenomena that operate over different length and time scales and which support integration and data exchange across scales. Located at the end of the CCS chain, the performance of the geological CO2 storage site has implications for many other parts of the CCS infrastructure. For instance, how easily the store accepts injected CO2 will govern in part the number of wells required and wellhead design. The pressure of fluids already present in a store, and how this pressure is connected, will be a factor in how much CO2 the store will ultimately hold. Each potential CO2 storage site may be defined by a set of geological and geotechnical parameters. Variation in these parameters and their interaction at different scales results in each site being unique. As one of the objectives of this proposal BGS will construct a series of injection and storage models that will reflect the widely differing characteristics of a CO2 storage complex and test how variations in key parameters for each model affect the whole CCS system. Accurate characterisation of a realistic set of CO2 stores will be a crucial component in the construction of the whole systems model. Several types of geological storage mechanisms, typical of offshore UK oil and gas fields and saline aquifers, will be identified to reflect the different storage options that may be available in future CCS projects. Using actual examples, each potential storage site will be mapped and characterised. Static storage capacity will be calculated and will account for the limiting effect of pressure build-up in the reservoir and possible mitigation options. A 3D model of each site will be constructed and populated with relevant geological and geotechnical information derived from existing accessible datasets, interpretations and published information. Use will be made of data and results from other relevant CCS studies including CASSEM and the Scottish Regional Study. Where specific in situ information is unobtainable, data from analogues will be utilised. The results will be used in Work Packages 1 and 5 of this bid.