Review and analysis of energy storage systems by hydro-pumping to support a mix of electricity generation with a high percentage of renewables

Abstract

In some countries the planning of the electricity generation mix for the future includes a considerable increase in Renewable Energy (RE) to reduce the emissions caused by the use of fossil fuels. This trend can be reinforced if the installed power capacity of nuclear and coal plants is considerably decreased. On the other hand future electricity demand seems to increase due to population growth and greater domestic electrification, especially if transport electrification is tackled. The combination of these factors may result in an ever greater decline in Security of Supply (SoS), mainly due to the stochastic nature of electricity supply and demand behaviour. To achieve an acceptable level of SoS when introducing renewable energy into the grid it is necessary to increase storage capacity and tackle other measures such as demand management. Many energy storage technologies can be found, and Pumped Hydro Energy Storage (PHES) is recognised as the most mature, though other technologies such as batteries are also available. In this paper, we first review PHES and its ability to support intermittent generation from energy plants, such as wind and solar, preventing energy losses and storing energy for use at times of high demand; second we analyse the performance of PHES in Spain over five years (2014-2018); our conclusion confirms that adequate SoS cannot be guaranteed with PHES management of the kind observed in the past.