Carbon capture and storage (CCS) combines several techniques in order to capture carbon dioxide emitted by industrial and energy production processes, transport it and store it in geological reservoirs, so as to isolate it from the atmosphere for long time periods. This technology was invented in the 1970s by researchers and industrialists. A few industrial projects applying CCS are today in different parts of the world. In the EU, a CCS policy emerged during the last decade. The European Commission, in partnership with industry players, has committed to a process of CCS "demonstration", aiming to develop 10 large-scale demonstrators by 2015. The emergence of EU CCS policy was marked by intense debates and local conflicts, especially with regard to the risks associated with potential leakages of CO2 in the short term (acidification of surface media or groundwater) or in the long term (CCS claimed to be ineffective in the fight against climate change). These discussions have also addressed the high cost and the relevance (end-of-pipe technology) of the CCS option in comparison with other CO2 mitigation options (reduction in energy demand, development of low-carbon energy technologies). This paper analyzes the relationship between CCS demonstration and the definition of the associated risks, by looking at the way in which protagonists involved in the CCS policy process resort to normative, stabilized or emerging risk frameworks.