Pumped hydropower storage in closed open-pit lignite mines can provide substantial contributions to the European energy transition

Decommissioning lignite mines supports the European Union’s (EU) climate targets of 55% net greenhouse gas reduction by 2030 and climate neutrality by 2050. One way to reach these objectives is by increasing the share of renewables in the energy mix. However, increasing the share of variable renewable energy requires flexible and scalable storage. Transforming decommissioned open-pit lignite mines into Pumped Hydropower Storage (PHS) sites offers a solution that enhances energy security while enabling regional economic transition. Multiple lignite mines have been decommissioned or scheduled for closure between 2038 and 2045. Prior studies on utility-scale storage focused primarily on existing reservoirs, with only a limited number exploring the potential of open-pit mines. The present study evaluated 164 EU open-pit lignite mines and identified 50 technically feasible sites for PHS implementation. Two scenarios incorporating assumptions focusing on load balancing and demand management were assessed. Maximising power capacity for short-term load balancing yielded 9.6 GW power and 117 GWh storage, representing approximately 21% of current EU installed PHS capacity and a 45% storage increase. In contrast, maximising energy storage for seasonal demand resulted in lower power capacity of 5.4 GW (12% of EU total) but significantly higher storage capacity of 13 TWh, a 4,860% increase. These findings highlight the substantial potential of utilising closed open-pit lignite mines for PHS to support the EU’s energy transition, directly aligning with the EU Green Deal and energy security objectives by a utility-scale solution that optimises renewable energy capacity utilisation.