On 14/07/2012 15:34, The Natural Philosopher wrote:
you can work it out from the drop - usually 3-4 feet - and the volume of
water.

The short answer is a couple of bhp if you are lucky. say 1.5KW. maybe
enough to keep a single house going. But not to boil a kettle as well.


That's a bit low. In fact probably by an order of magnitude, or maybe
even two.

http://www.bbc.co.uk/news/uk-england-berkshire-12983559

says the plans for Newbury on the Kennet could give 22kW, and the Kennet
is neither very big nor very steep. I wouldn't be surprised if one on
every lock on the Thames could get as much as a megawatt.

Obviously finding enough such rivers to make 40GW might be hard. :/

Andy