 The Cruachan station temporarily stores energy at times of low demand , and releases it at times of high demand , when electricity prices are higher , reducing the maximum power that must be provided by power stations . It is also used to cope with sudden surges in the demand for electricity , such as at the end of television programmes . Despite the use of some rainwater , Cruachan is not a net generator of electricity : it uses more energy for pumping water and spinning its turbines than it generates . 
