Applied risk and consequence analysis for CO₂ storage projects – the Captain X storage site, offshore UK (Acorn)

The Acorn project is a full-chain industrial CCS project, with collaboration between seven organizations across Europe. The aim of the project is to produce a technical development plan for a CCS hub that will capture CO₂ emissions and store the CO₂ at offshore subsurface storage sites under the North Sea. To assess the risk of leakage from the primary reservoir of the Captain X storage site, a risk assessment methodology based on expert elicitation was applied. Eleven leakage scenarios were designed which describe all possible leakage pathways, and a series of features, events and processes which will either enhance or reduce the likelihood and the severity of the leakage scenarios were discussed. The output of the assessment is a serious of risk matrices and spider diagrams combining the risk as well as the impact of consequences of potential leakage.