Flowing water is a renewable energy source, and modern hydroelectric power stations can convert at least 90% of this energy into electricity. But sites in the UK where water power can be harnessed on a large scale are very limited.
Large-scale hydroelectric power stations must dam valleys to create reservoirs in which to store water. For the installation to include pumped storage – to store energy for later use – two reservoirs must be situated close together but at different heights.
Not many sites in the UK meet these conditions. Most of those that do are in the Scottish Highlands and are already home to large-scale hydropower schemes. In 2014, hydro generated 1.91% of UK electricity. Due to the lack of other suitable sites, this figure is unlikely to increase significantly.
It is likely that opportunities to develop further large scale hydro projects are limited because of environmental concerns, and because most of the economically attractive sites have already been used. DECC (2010 figures) has cited studies which estimate the remaining viable hydro potential as between 850MW and 1500MW.
Existing UK large-scale hydroelectric power stations will continue to contribute to our electricity supply and help to meet renewable energy targets.