There are three main categories used to define the output from hydroelectric power:
- large-scale capacity (hydro plant producing more than 20 megawatts)
- small-scale capacity (hydro plant producing less than 20 megawatts)
- micro-scale capacity (hydro plant producing less than 100 kilowatts)
The total hydroelectric installed capacity in the UK in 2010 was approximately 1650 megawatts, which is 1.8% of the current total UK generating capacity and 18% of renewable electricity generation capacity.
How will hydroelectric power contribute to the renewables targets?
The UK currently generates about 1.3% (5000GKh) of its electricity from hydroelectric schemes – most of which are large-scale schemes in the Scottish Highlands. Hydroelectric energy uses proven and efficient technology; the most modern plants have energy conversion efficiencies of 90% and above. Hydro has a typical load factor of 35-40%.
Future development
It is unlikely we will see again the scale of development witnessed in the UK in the 1950s and 1960s. Opportunities to use this technology on a large scale are now limited, not only because of environmental concerns but also because many of the most economically attractive sites for schemes have already been used. However, it is important we exploit our remaining small-scale hydro resources in a sustainable way.
Some old watermills are also being refurbished and brought back into the energy supply network.
Recent studies estimate there is a remaining viable hydro potential of 850-1550MW in the UK. This represents approximately 1-2% of current UK generating capacity and so would make a modest but useful contribution to UK renewable energy and emission reduction targets. There are a number of steps that have to be considered before a scheme can be built, e.g. scheme economics, environmental permits, planning consent and connection to the local electricity network.