On the stumbledupon.com site I found this clip.
So what’s happening here?
So how much electricity are we talking about here? Any chance of hanging a couple of Triple40XXXXXXX cans up where a water fall goes through them and getting enough electricity to run a small town?
You don’t get something for nothing.
It would take way, way, way more power to pump the water than you would get back.
These sort of generators are just novelty items - there are several other similar devices - Van Der Graff Generators and Wimhurst Machines for two.
The closest thing that could possibly give “free” power is lightning, which works on a similar principle. So far, it hasn’t been possible to harness lightning, and probably never will be. It also may not be a good idea, but that’s a different story.
Beowulf’s link provides some examples with the amperage of electricity generated. In one example using a garden hose as a sort of waterfall substitute, only 2.5 microamps is generated. Not shabby for a cool experiment you can rig up with household items, but it’s not going to power a city as efficiently as hydroelectric turbines.
It’s actually a great commentary on the difference between power and volts. You can create devices like this that generate thousands or even millions of volts, but very little actual power.