Repurposing decommissioned lignite mines for pumped hydropower storage: a key enabler of EU renewable integration and climate goals

Decommissioning lignite mines aligns with the EU’s climate goals of reducing greenhouse gas emissions by 55% by 2030 and achieving climate neutrality by 2050. A key strategy involves expanding renewable energy, which demands flexible and scalable storage to manage intermittency. Repurposing decommissioned open-pit lignite mines into Pumped Hydropower Storage (PHS) facilities offers a promising solution, enhancing energy security while supporting regional economic transformation. Over the next two decades, numerous EU lignite mines are scheduled for closure between 2038 and 2045, presenting a unique opportunity for sustainable redevelopment.

While prior research has largely focused on conventional reservoirs, the potential of repurposing abandoned mines for PHS remains underexplored. This study fills that gap by evaluating over 140 closed or soon-to-be-closed open-pit lignite mines across the EU. It identifies 50 sites as technically feasible for PHS development, based on topography, hydrology, and grid connectivity. Two operational scenarios were analyzed: short-term load balancing and long-term seasonal storage.

In the load-balancing scenario - optimised for grid stability and peak demand response - the 50 sites could deliver up to 9.6 GW of power capacity and 117 GWh of energy storage. This represents 21% of the EU’s current PHS capacity and would increase total capacity by 45%, significantly boosting grid flexibility. In contrast, the seasonal storage scenario prioritizes long-duration energy storage, yielding 5.4 GW of power (12% of current EU PHS capacity) but a substantial 13 TWh of storage - 4,860% more than existing levels. This vast storage potential could help overcome seasonal mismatches between renewable supply and demand, particularly in solar- and wind-rich regions.

These findings underscore the transformative potential of repurposing lignite mines into PHS facilities. By leveraging existing geological features and infrastructure, such projects can reduce development costs and environmental impact compared to greenfield constructions. Moreover, they support just transition initiatives by revitalizing post-mining regions through clean energy investment, job creation, and industrial diversification. The integration of PHS into the energy system enhances renewable energy utilization, reduces reliance on fossil fuels, and strengthens energy independence - key pillars of the EU Green Deal. As the bloc accelerates its clean energy transition, closed lignite mines emerge as strategic assets for utility-scale storage. With careful planning and policy support, these sites can play a pivotal role in building a resilient, low-carbon energy future, directly contributing to climate targets and long-term energy security across Europe.

References
Ernst, P., Kempka, T. Pumped hydropower storage in closed open-pit lignite mines can provide substantial contributions to the European energy transition. Journal of Sustainable Energy and Assessments, in review.