An Exploratory Economic Analysis of Underground Pumped-Storage Hydro Power Plants in Abandoned Deep Coal Mines

Reinhard Madlener,Jan Martin Specht

doi:10.3390/en13215634

Abstract

This study researches the concept of underground pumped-storage hydro power plants in closed-down underground hard coal mines in Germany. After a review on how this could be realized technically, an economic feasibility analysis is presented, with a particular focus on the costs for the underground storage reservoir. The analysis is performed for different lower (i.e., underground) reservoir sizes and temporal arbitrage potentials (peak/off-peak electricity price spreads), and cost uncertainty is dealt with by means of a Monte Carlo simulation for two distinct head heights. The findings regarding costs and acceptability are compared with those of a classic (on-surface) pumped-storage hydro power plant in a mountainous area. Based on a techno-economic evaluation we conclude that under favorable conditions the realization of underground pumped-storage hydro power (UPSHP) plants seems both technically feasible and economically reasonable. More specifically, an extension of a tubular system seems the most promising option. A UPSHP plant in a mineshaft is probably slightly more expensive than a conventional one, an outcome that depends strongly on the feasible head height. However, the significant reduction of the adverse impacts on the landscape and on local residents, as well as a potentially large number of feasible sites in flat terrain, could make UPSHPs an interesting option for the future energy transition, not just in Germany but worldwide at sites where underground mining is being abandoned.

Highlights

Since the 1980s, the political will to reduce dependency on nuclear and fossil energy sources has risen in Germany [1]
+/− Since underground pumped-storage hydro power (UPSHP) is a novel concept, the engineering budget was increased by about 10% in the standard case
From our broad technical and exploratory assessment, we can conclude that the construction of a subsurface storage reservoir is in principle possible

Summary

Introduction

Since the 1980s, the political will to reduce dependency on nuclear and fossil energy sources has risen in Germany [1]. The promotion of renewables is in the political interest of the German federal government and is pushed by a dedicated regulatory framework [2,3]. Due to these favorable boundary conditions, renewable power production has increased tremendously over the last years. This development raises problems in terms of safeguarding grid stability [4], as wind and solar power are intermittent and subject to strong seasonal and weather-dependent variation.

Methods

Findings

Discussion

Conclusion