The UK generated around 1.8% of its electricity from hydro-electric facilities in 2012, which equates to 1.65GW of installed electrical generating capacity. A significant proportion of this was from large scale hydro-electric schemes. There are four large scale conventional hydroelectric power stations and large run-of-river schemes in the Uk which produce approximately 5,000GWh per annum. The potential for further practical and viable hydro-electricity power stations in the UK is estimated to be in the region of 146 to 248 MW for England and Wales, and up to 2,593 MW for Scotland. The British Hydro Association has identified a larger number of viable sites, due to improvements in the available technology and the economics of ROCs and FITSs.
Large scale hydro schemes utilise dams that impound water in a reservoir, creating a large head of water with significant stored potential energy. The reservoir feeds large turbines and generators that are usually located within the dam itself and can rapidly respond to spikes in demand for electricity.