How much energy could be harnessed from rain falling?

Question

Each raindrop, for instance weighs or contains gravitational force, falling from the clouds. If we could design a collection system that could harness the raindrops as they fall from the sky, could that become an alternative energy source?

I realize these drops accumulate in rivers and streams and we have hydroelectric dams and such, but what about just designing a collection field where the drop's gravitational energy transfers to power that can be used, electrical or what have you.

Answer 1

Your idea is good.

You can device a small generator through this to lamp few LED or so.

So, next time, there is a power-cut you will have light through your generator.

: : : : : : : : : : : : : :: : : : : : :

: : : : : :RAIN DROPS : : : : :

: : : : : : : : : : : : : :: : : : : : :

| - - Water - - - - - - - - - - - - -|  

\__________  ___________/

. . . . . . . . . | |

. . . . . . . . . | |                                        

| . . . . .GENERATOR. . .  . . . . . . . . .( Light )

|. . . . . . .   \    /    ___________________|  |

|. . . . . . .  O      ____________________|      

|. . . . . . .  /     \  

                        

Answer 2

The Grand Coulee Dam in WA utilizes 110,000 cubic feet of water per second. Lets just assume you get 60 inches of rain per year  or 1.5855(10^-7) feet per second (rain forest level) at a constant rate. To capture as much water as the Coulee Dam would require an area of 6.9379(10^11) square feet which equals 24886 square miles which is roughly the size of the state of West Virginia.

Answer 3

When considering an R&D proposal, we look at desirability and we look at feasibility.  If the project is not both desirable and feasible, we don't do it.

So is direct harnessing of raindrop energy desirable?  What would be the benefits, say, over using hydroelectric dams where the raindrops are collected as lakes?  None I can think of.  In fact, by interdicting the raindrops, we might be denying crops and plants the water needed to grow.

Then, is raindrop energy feasible?  This has to address economic, political, and technological feasibility.  Dispersed over hundreds if not thousands of square miles, the device to convert raindrop kinetic energy into, say, electrical energy would have to be equally as expansive.  Then all those tiny voltages from each conversion would require routing to some collection point from which distribution to users could be done.  And all this would have to be funded somethow.

Politically, this would be a nightmare.  The widespread raindrop collection and conversion devices would encroach on farmers, rurual residents, industrial sites, central business districts, and so on.  That results because of the widespread dispersion of raindrops.  And to a point, where rain is plentiful, we will find people living for the most part.  To iimplement this R&D project would require invoking eminent domain over all those privately held places.

Finally, is the technology feasible?  As raindrops fall randomly over wide areas, what would we use to effectively and efficiently collect these individual drops when we cannot predict where they will fall?  A flat sheet of microsensors might do it, but over hundreds of square miles?  I think not.  And if the raindrops hit a sheet, where would they go after the impact?  If none of the water soaked into the ground, the streams and lakes might very well fill and overflow.

If I were senior management deciding to go or no go for this project, I'd say it is a no go.  It is neither desirable nor feasible.

Answer 4

You're right that falling raindrops have gobs of kinetic energy.  If you can concentrate all that rainfall at one small spot and have it pour over a hydroelectric dam, it would generate a lot of electrical power.

The problem is concentrating those billions raindrops.  Even small storm drop millions of gallons of water over hundreds of square miles.  It's too dispersed to be practical.

However, if rain falls upriver from a hydroelectric dam, the added water will increase the electrical power the dam generates.  That's probably not quite what you had in mind, but at least it's some added power, and it's free.

Answer 5

The machine you'd use must be very big, if you'll get energy straight from the rain, so that it will be affected by more rain, not just some drops. It is more economically-wise to just get power from rain that is already collected, like in river. Remember, more mass most likely has more energy.