IN reply to Tony Ward of Lawrenny, Western Telegraph, July 10; of course, British hydro power should be exploited; unfortunately, the resource is far smaller than he supposes.

The Environment Agency has published Potential Sites of Hydropower Opportunity; the

webpage was last updated on March 15.

From the report summary, 25,935 locations were identified in England and Wales, with a total potential capacity of 1,178 Megawatts. The British Hydropower Association gives a rougher total of 2,000 Megawatts for total UK unexploited hydro potential.

Meanwhile, excluding smaller wind turbines (under 100 kW), in the UK there are 13,051 Megawatts of installed onshore wind power capacity and 8,483 Megawatts of offshore wind power capacity (Renewable UK UKWED database).

To give an idea of the total resource, various engineering and strategy reports propose up to 35,000 Megawatts of onshore capacity and 75,000 Megawatts offshore by the mid-2030s, reflecting the need to decarbonise UK heating and transport using electrical technologies.

It is unfortunately not as straightforward as Mr Ward supposes to develop a hydro power site, due in particular to wildlife considerations: almost half (46 per cent) of the locations listed by the EA are classified as highly sensitive, mostly because of the presence of migratory fish species such as salmon and eel.

So, while all feasible renewable energy resources need harnessing and hydro can make a useful contribution, as the Committee on Climate Change confirms we are going to need a large expansion of onshore and offshore wind and solar PV to achieve UK zero carbon targets.