Pumped storage technology combined with thermal energy storage: Power station and pressure tunnel concept

Water power is the oldest and most-used energy source for provision of mechanical work and electricity generation. Furthermore pumped storage hydropower is ranked as the most reliable and efficient storage technology for electricity. The energy carrier water is also the most commonly-used thermal storage medium due to its high specific heat capacity. In a study, the combination of electrical and thermal energy storage in a pumped storage power station is investigated in order to cover two energy-intensive sectors with the economical double use of water as an energy medium. With this double application the energy output compared to separate storage usage can be considerably increased.

Underground power stations are independent of topography, so this storage concept can be used for district heating supply. One possible vision is to stor solar energy into the water reservoir of a pumped storage power station in the summer months and transfer it in the high-demand winter months. In order that pumped storage power stations can keep functioning at high and seasonally fluctuating water temperatures and simultaneously store thermal energy efficiently, some adaptations of the structures and the pressure tunnel layout are necessary.