Navitron Renewable Energy and Sustainability Forum

General Renewable Topics => Inventions, Ideas, Innovation, Bodges etc => Topic started by: Ivan on May 25, 2008, 06:45:31 PM



Title: Electricity from rain
Post by: Ivan on May 25, 2008, 06:45:31 PM
Raindrops develop charge as they fall through the air. Various factors affect this - how dry the air is, how much dust in it, how warm, droplet size etc. I did a few calculations to see how much energy this could develop (people often tell me they'd buy a device that generates power from rain!).

Starting point facts:

Each raindrop holds around 0.031 esu (http://ams.allenpress.com/perlserv/?request=get-abstract&doi=10.1175%2F1520-0469(1953)010%3C0279%3ARCAEFI%3E2.0.CO%3B2&ct=1 )

1300-2700 drops fall per m2 per sec in a storm (equivalent to  0.6 1 mm of rain/min ) ( http://www.google.co.uk/search?hl=en&q=raindrops+m2+hour&btnG=Google+Search&meta= )

1 Coulomb = 3109 esu. (http://www2.physics.utoronto.ca/~phy326/Units.htm  )

Calculation

So, (2000 raindrops x 0.031)/3x109 Coulombs of electricity falls per second per m2 [Coulomb/sec = amps]
=0.02uA.

I guess this charge could be collected using a metal plate, metalised plastic, or wire mesh which the rain falls onto.

I've no idea what the voltage is - couldn't find that anywhere. Let's assume it's 100v. So the power would be 2uW. So if we wanted to generate 100W, we'd need 50km2 of capture plate. Hmm. Back to the drawing board perhaps