David asked: >> Why don't BW fit waterwheels and/or water turbines to all of their >> lock by-wash weirs and river weirs? These would make use excess >> water flowing over the weirs to produce green electricity - which BW >> could sell to make some money.
To which John replied: > The immediate question that comes to mind is pay back period - how long > would it take (maintenance included) to actually make a profit. It > wouldn't surprise me if the answer came back at something like 50 years > before capital investment and maintenance was paid back and profit > actually began (indeed probably more when you consider the cost of > connection to the grid as well). I've just done a little reading on this. Underground by-washes could be adapted for propeller turbines without too much difficulty and in locations where there is 3m or more head of water, Pedley Wheels also look viable. Installation costs are in the region of £3-6k / kW power generated but that's a one off and installations should last 30+ years. I reckon a by-wash might generate 2-3 kW based on my own quick water flow guestimates. Not enough to get rich on but useful in locations with no local mains power... Steve NB Bream
