The topic of this briefing is energy storage. Leaders from 17 countries were interviewed on topics exploring recent progress in terms of technology, business models and enabling policies. This document showcases these in 10 case studies. While the brief addresses energy storage as a whole, most insights are focused on electrical storage. The research highlighted that today’s mainstream storage technologies are unlikely to be sufficient to meet future flexibility requirements resulting from further decentralisation and decarbonisation efforts. Furthermore, a restricted focus on lithium-ion batteries is putting the development of more cost-effective alternative technologies at risk.