Despite its clear importance globally, hydro power in the United Kingdom falls well behind other renewable sources , such as wind power, in its contribution to the energy mix. In 2019, some 5,464 gigawatt hours of hydroelectricity were generated in the UK, with the majority generated by large-scale hydro plants. Whilst the generation of such plants has fluctuated over the past decade, small-scale hydroelectricity generation has been steadily increasing.
The majority of the UK’s hydroelectricity is generated outside of England, with the biggest large-scale hydro plant located in Scotland. The Glendoe Hydro plant has an installed capacity of 100 megawatts and is operated by the energy company SSE plc. Formerly Scottish and Southern Energy plc, SSE operates numerous conventional hydro plants across the UK, as well as pumped storage schemes. In 2020, the company had a generation capacity of 1,159 megawatts for hydro and 300 megawatts for pumped storage. In the same year the company's generation output from conventional hydro was 3,743 gigawatt-hours.