Sir – I read with interest Penny Clover’s letter (December 23).

I, too, had often wondered if anyone would ever be able to harness the power of the Thames weir water. I followed with interest your progress in the Herald and am sorry it failed.

I ran a hydroelectric plant for a number of years in Zambia, our only power for a bush Mission Hospital, Hansen Centre (leprosarium) and staff quarters.

Ours ran fine, even at the end of the dry season we could get enough power for a few hours for lighting and emergencies.

I visited many hydro plants in Africa, some worked quite well, most used some form of Archimedes screw from vertical to almost horizontal.

We used a barrel turbine set into a concrete dam with about a two-metre drop.

I was curious why you chose to use an Archimedes turbine while a wide vaned barrel would, I think, have given you much more power and have been successful.

John Eaton
Sovereign Place