SIR - A topical update on the issue of hydro-electric power.

In a very timely announcement, it was revealed last week that 68 sites on Yorkshire and Lancashire rivers, including the Calder, Wharfe and Aire, have been identified as having potential for hydro-power generation from their natural flow.

These sites alone are estimated to have the capacity to power 18,000 homes, using a modern version of the Archimedes screw principle.

So, no "Niagara Falls" volume needed after all, and no allegedly "underpowered mill-race" issues either.

I think that's a green' game, set and match to me.

Graham Hoyle, Kirkbourne Grove, Baildon