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. Key criticalities identified included such issues as the abundance, availability and security of supply of critical raw materials; supply chain complexity, location and resilience; the sustainability and environmental impacts of energy technologies; public opinion and acceptability; affordability; and digital vulnerabilities. Specific criticalities by technology value chain have been identified and prioritised and corresponding research and innovation (R&I) actions have been proposed tailored to those specific issues. The R&I action plan comprises 30 actions that can be implemented at European Union (EU) and national levels to address the criticalities identified, with the top 9 highest-priority R&I actions identified based on a SWOT (strengths, weaknesses, opportunities and threats) analysis.