Abstract The IMPACTS project has the objective to develop the knowledge base of CO 2 quality required for establishing norms and regulations to ensure safe and reliable design, construction and operation of CO 2 pipelines and injection equipment, and safe long-term geological storage of CO 2 . More specifically for this paper, the project sets out to reveal the impacts of relevant impurities in the CO 2 stream on the design, operation and costs of the capture, transport and storage infrastructure and to provide recommendations for optimized CO 2 quality through techno-economic assessments. The areas covered include corrosion from water content in the CO 2 stream in combination with other impurities and the influences of impurities on transport, injection and storage processes and include estimates of the cost of measures to mitigate or prevent these impacts, or of adapting of CCS system design. A specifically designed CCS chain model is used to assess the impacts on a number of reference CCS chains, evaluating economic trade-offs to both understand the full-chain whole-life economics of certain CO 2 impurities at different levels and then to potentially optimize a purity specification for various sets of circumstances.