This paper reports the development of a tool to assess the environmental performance of carbon dioxide capture and storage (CCS) chains. The environmental assessment is done for the whole CCS chain. The tool has been designed to produce transparent and traceable results and is easy to work with. The tool is meant for a broad group of stakeholders for assessing CCS chains on their environmental performance. It provides insights into the environmental performance of CCS chains by using a learning-by-doing experience for users. It allows both knowledge sharing and stakeholder engagement so that view points of stakeholders are better understood and decision making on the deployment of CCS can be improved.