# I Is generating electricity from rain water efficient?

1. Apr 3, 2017

### DWT

From small generators attached to the gutters of your house to large ones in the storm sewers, is it efficient enough to make the effort?

2. Apr 3, 2017

### Staff: Mentor

This only depends on the available amount of rain. If you build a Hoover dam or dig the Niagara falls ...

3. Apr 3, 2017

### Staff: Mentor

Sure. If you can do it with a faucet, you can do it with a downspout. The faucet powered light in the picture costs only \$5.

But if you mean generate enough power to supply your house, no.

4. Apr 3, 2017

### Khashishi

Hydroelectric is just rainwater electricity on a larger scale. Rivers naturally collect rainwater from large areas.

5. Apr 3, 2017

### DWT

I think the rain gutter generators would be useful for "off the grid" households. Solar and wind are already popular I thought why not rain gutter/grey water pipe generators.
I have had this idea for a decade or so thought it was time to share it.

6. Apr 3, 2017

### CWatters

http://www.renewablesfirst.co.uk/hy...-power-could-i-generate-from-a-hydro-turbine/

Is 75% efficient good enough?

7. Apr 3, 2017

### jbriggs444

Is that the right measure of "efficiency"?

Say that you have 1 meter of rain per year on your 10 meter by 10 meter footprint for a total of 100 cubic meters = 100,000 kg of water. Say your eaves are 10 meters above ground for a total of one million kilogram-meters of lift. Gravity is 10 meters per second^2 so that's about 10 million Joules.

One kilowatt hour is 3.6 million Joules and costs about a dime.

That means that a year's worth of rainwater on your rooftop generates about 30 cents worth of electricity.

8. Apr 3, 2017

### Staff: Mentor

It's awesome to have ideas, but as jb Riggs showed, you can quickly do some basic calculations to see if they might be viable...to get them out of your head and at least on to the back of a napkin. We can help!