On Tue, 19 Oct 2010 10:51:13 +0100, The Natural Philosopher wrote:

But we do have an awful lot of water reservoirs obstenishly for
drinking water but most if not all let down water all the time to
keep the rivers below them flowing.

Golly. the fact that they are full might have something to do with that?

They still let down water irrespectively of the level in the
reservoir for the rivers below. If they didn't there would be an
awful lot of dry rivers in the summer when the level in the reservoir
drops below the spill way.

And teh fact teh water is needed belwo them for more than just paddling
in never crossed your mind?

They may well abstract from the river lower down for treatment, using
the river as a cheap pipeline. Either way, let down to feed the
treatment works or let down to keep the river alive, you still have
the energy available at the reservoir from that let down.

One could harness this let down for power generation.

A couple of kilowatts maybe. On and off.

I'm talking about decent sized reservoirs with a large dam. 20m head
and 5,000l/sec gives about 500kW. This let down is 24/7, pretty sure
the water co's would have to get permission from the EA to cut it
off.

People simply have no idea of the scale odd power geeratuiio, and how
much a coal or nuclear station puts out, and how little a lump of water
falling a couple of hundred feet does.

I'm well aware of the numbers. But 24/7 power for not much more than
the cost of a building and turbine set at the foot of an existing
damn must be very good value for money. Even maintenance costs are
very low.

--
Cheers
Dave.