micro hydro generator question

[wk1776]

i have recently been browsing some hydro sites, and it sounds like a good idea, the only problem is that i live in the city with no near running water supply.  i was wondering if i were to use a holding tank for the water and a pump to spin a water wheel, if it would create more power than the pump uses.  i was looking at a 1/2 hp pump that pumps 2500 gph.

[geoffd]

Due to the Law of Conservation of Energy it would only be of benefit if you had a source of 'free' water such as filling the holding tank by collecting rain water.

You can only take out the amount of energy you store minus the inefficency of the system.  So if you pump up enough water to give you 1000W it will cost you 1000W of energy plus the inefficency of the pump e.g. 10%  so it will cost 1100W.  Then you run that through a hydro that is only 70% or less efficient, so you will get 0.7 * 1100 = 770 W of electricity.  So it has cost you 1100W to produce 770W.

If you have rainwater and can collect enough the run the system then of course it is 'free' but you would need quite a lot of water to produce a useful amount of electricity.

Cheers

Geoff

[drdongle]

Thee ant no free lunch

[pyrocasto]

What about roadkill?

[drdongle]

What snake jerky? it aint free if you have to scape it up.....