Power generation using the potential energy stored in our tanks?

[Lampshade]

The problem with doing a generator on the tank is the very small amount of pressure you get from the free fall of 6' of head pressure even at 3000gph is only 54W of power even with 100% efficiency(you'll probably have 50%). To save it in batteries would be a good idea, but you'd have to look at the cost per watt of the energy and see if it's really better than just sucking from the grid to recharge batteries.
http://www.fancygaphtrn.com/calculat...wer-calculator

The easier way to cheat the system especially if you're on un-metered water is to just use your water line to your house :P. 80psi = 185' of head pressure. It would produce anytime you use water, and in a power outage, you could dump a little down the drain, haha. The solar idea would work, it's getting very cheap now to produce solar power and even in cloudy/rainy BC with some of the cheapest energy costs in the world it's becoming feasible to do it.

[FitoPharmer]

I thought these type of Stirling engine energy recovery systems were neat for saving some money. Just have to figure out if you can use them for a reef tank. Maybe run water cooled halide shades then run it through one of these

http://www.greenoptimistic.com/2010/...irling-engine/

There are even versions that can take the energy left over from hot showers, dish washing, laundery, ect....

[mark]

A zero cost display is like perpetual motion, good luck, other than maybe go coral farming or fish raising to try to break even through sales.

[asylumdown]

I totally agree on the overflow recoup not being feasible, unless of course your system was gigantic. Cool idea though, it's like regenerative breaking on a hybrid car.

One thing I've heard of people doing to make their tanks more 'green' is to reuse the waste heat in other areas of the home. The one tank I saw this done on was like 1200 gallons or something ridiculous, and it was powered by umpteen million 400 watt MHs. The guy who built it lived in Minnesota or somewhere with horrible winters like that, so he built his house's HVAC system around the tank. In the winter exhaust heat from the lights would be used to heat the air in his forced air system, offsetting the heating bill for his house. In the summer when it wasn't needed, he'd just switch it so the tank exhaust would vent outside.