Long-term prospects for compressed air storage

The compressed air storage (CAS) concept has been reviewed in the light of the long-term requirement for energy storage to effect load following in a predominantly nuclear generating system. This requirement would eventually lead to the operation of storage plant on a daily cycle of storing energy for 6–8 h and generating for 12–16 h. Conventional CAS schemes, typified by the Nordwestdeutchen Kraftwerke (NWK) installation in West Germany, are shown to be incapable of fulfilling this duty on merit.The basic concept is then re-examined and a novel development is proposed which, by using uncooled compressors and conserving the compression energy, constitutes a true energy storage scheme requiring no fuel other than the off-peak energy taken from the electrical grid. The efficiency and other performance characteristics of this proposal are discussed.The capital cost of an 8 GWh storage scheme is tentatively put at £125–175/kW (at 1974 price levels), depending on the air store construction, well within the £200/kW cost target which storage plant would need to meet to be of interest for storing off-peak nuclear power by the end of the present century. It is concluded that, once developed, CAS schemes which incorporate heat storage could provide an attractive method for storing off-peak electricity.