This project addresses the fundamentally important and urgent issue regarding the accurate predictions of fluid phase, discharge rate, emergency isolation and subsequent atmospheric dispersion during accidental releases from pressurised CO2 pipelines to be employed as an integral part of large scale Carbon Capture and Storage (CCS) chain. This information is pivotal to quantifying all the hazard consequences associated with CO2 pipeline failure forming the basis for emergency response planning and determining minimum safe distances to populated areas. The development of state of the art multiphase heterogeneous discharge and dispersion models for predicting the correct fluid phase during the discharge process will be of particular importance given the very different hazard profiles of CO2 in the gas and solid states. Model validations will be based on both small scale controlled laboratory conditions as well as large scale field trials using a unique CCS facility in China. A cost/benefit analysis will be performed to determine the optimum level of impurities in the captured CO2 stream based on safety and economic considerations. The work proposed, carried out over a period of 36 months will embody the understanding gained within safety and risk assessment tools that can be used for evaluating the adequacy of controls in CO2 pipelines, with best practice guidelines also being developed. The proposal addresses the main themes of the Collaborative Call in that it "has a predominant research component and its successful outcome would allow the safe and commercial deployment of large scale near zero emission power generation technology based on CCS”. The project also enjoys strategic leadership from members the Carbon Sequestration Leadership Forum and highly relevant collaboration with the world’s second largest and fastest producer of CO2, China.