Novel concepts of increasing energy storage capacity at Pumped Storage Power plants

Abstract

The paper presents two novel concepts for increasing energy storage capacity at Pumped Hydro Storage (PHS) plants that are planned, being constructed or already exist. Both concepts make use of compressed air, but unlike other storage technologies that utilize compressed air, the air is not intended as the energy storage itself, it is a working fluid for moving water. By using compressed air, it is possible to utilize storage volumes that are positioned below the original upper reservoir in PHS plants. The two concepts presented here uses this principle, one by inflatable air bags positioned below the lower reservoir level, and the other by excavation of underground reservoirs that serve as the increased storage volume. The necessary operation comes at an efficiency penalty, but the energy storage reservoir will have an increase in size, without any new dam being built or existing water levels rise. This makes it ideal for retrofitting at existing PHS plants, which would increase the energy storage capacity as well as making it possible to install additional power generating capacity.