The deployment of grid-scale electricity storage, including battery energy storage systems (BESS), has accelerated with the transition toward a decarbonised and flexible electricity system and the electrification of the wider energy system. The emergence of storage and its rapid growth has demanded new public policy responses.This report shows that Ireland has been a ‘leader’ on the deployment of BESS in relative terms. This is likely a result of its need for flexibility in the context of high penetration of variable renewable electricity sources (VRES) and a paucity of alternative sources of flexibilities, especially in the short term. The deployment of BESS has been supported by key policies, including ambitious high-level goals for GHG emissions and renewable energy (RE) by 2030 and climate policies that acknowledge the important role of storage; policies that put in place the DS3 market for system services; and the establishment of capacity markets that accommodate storage. Ireland is now at a critical juncture in the development of its storage policies. It is therefore timely to take lessons from Ireland’s experience to date and from international experiences.Our comparative analysis of twelve leading and promising markets for storage finds great diversity in BESS policy mixes. While government intervention seems universally necessary in order to facilitate the development of storage and BESS, there is no single successful policy formula. The development of BESS is highly dynamic, and in many cases the full effects of current policy developments have yet to play out, so that the promising markets of the early 2020s may become leaders by the end of the decade. We identify several common markers of policy leadership.
• Today’s leaders on BESS were early starters in the early 2010s. This underlines the medium- and long-term effects of storage policies;
• Many leaders and promising markets have included a definition of storage in legislation and have recognised storage in other regulatory frameworks;
• They have established and regulated markets, including for system services, capacity, and arbitrage; leaders have also started to define a role in these markets for Long Duration Energy Storage (LDES);
• There is a wide variety of financial supports available across the twelve countries studied;
• While the study does not provide a comprehensive overview of R&D policies, it is evident from individual cases like the UK and South Korea that some leader...