I submitted this project to Google but that contest seems to have gone by the wayside so I’m posting it here. The idea was for a sort of solar powered micro-hydro generator.
It only takes about 10' of "head" to create usable micro-hydro. That’s not hard to make happen from a technological standpoint.
Take two 55 gallon barrels and put one 15' - 20' above the other one on four large 4x4 posts with 4x4 cross-members to hold it up.
Run a 1" hose in a spiral down the side of one of the posts and into a nozzle in the lid of the bottom barrel. The nozzel obviously sprays the micro-hydro wheel which is directly connected to a generator head on top of the lid. Output the electricity to a charge controller, a battery bank, and an inverter.
At the bottom of the barrel put a solar powered pump that pumps the water back to the top.
On top of the upper barrel put a large collection funnel with a weight-controller flapper valve so that when it rains it doesn't fill the barrel until there's enough rain to open the valve. This reduces evaporation. Also add an overflow that goes directly into the micro-hydro feed hose.
That means if it's raining the rain powers the micro-hydro but leaves the barrel on top full. When it's sunny the solar pump refills the top barrel. (Obviously with a float valve to control when the top barrel releases into the lower one.)
It probably wouldn't be constantly running but it would certainly run often enough to put a repeated charge on the battery bank.
And if there's no rain you can always use human power to fill the upper barrel. ;-)
What do you think? I figured out it's build-able for about $2k including batteries.
Not a perpetual motion machine! There is plenty of loss in this system. But I think it would run pretty well.