In the coming decades, energy security will depend less on uninterrupted access to fossil energy sources and will be increasingly determined by the access to clean energy technologies, materials and components. This study, delivered by RAND Europe, CE Delft and E3-Modelling for the European Commission, assessed the energy security challenges of value chains across 17 clean energy technologies now and looking to 2050, and identified 30 research and innovation actions to address them. The bespoke methodology brought together futures methods and macroeconomic modelling, value chains analysis and strategic decision-making tools to set out priorities for action.