Policies to double renewable energy across APEC economies by 2030 require additional storage to make best use of variable solar and wind generation. Population growth, urbanization and intensifying extreme climate events further threaten the resilience of electricity grids. This project report includes a policy brief and research on the pumped storage opportunities in each of the 21 APEC economies plus three Mekong region non-APEC economies. The report also summarizes findings from a workshop focused on capacity building for further deployment of pumped storage hydropower as an 'off the shelf' technology for large-scale electricity storage in APEC economies.