Water Tank vs Battery Bank ?

[russ]

Quote from the Wiki - [I]For example, 1000 kilograms of water (1 cubic meter) at the top of a 100 meter tower has a potential energy of about 0.272 kW

[MarineLiner]

Francis turbine

http://en.wikipedia.org/wiki/Francis_turbine?wasRedirected=true

Head: 10m up
Efficiency: 90%

[MarineLiner]

Pumped-storage hydroelectricity

http://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity?wasRedirected=true

[MarineLiner]

You use a small turbine to generate power from the head tank - then you need additional power to refil the head tank.
Net negative.
Both the turbine and pump are well under 100% efficiency - maybe 70%.

[russ]

You use a small turbine to generate power from the head tank - then you need additional power to refil the head tank. Net negative.

Both the turbine and pump are well under 100% efficiency - maybe 70%.

İt really only works for a free running stream or such.

[MarineLiner]

Example:
... using a 0.5 hp pump, for 9GPM, at 160', to 9,000 storage tank.
I will only pump on sunny days, about 4-5 hours a day.
That gets me 2,160 gallons on a 4 hour day.
The water is in a tank farm on a hill, and I just use the pressure from the tank, to do my water needs.
After a few days, I'll have all the tanks full, and can last a few cloudy days.
Daily needs are only about 200 gallons.
Storing the water on a hill, is more efficeint than using batteries to pump in the middle of the night.

[MarineLiner]

Same thing can bee applied with a elevated water tank.
You pump water up in the tank, and release it later to generate electricity. Sound cool but really inefficient.

Plus the volume of water required per kW generated is rather large.

[MarineLiner]

Something similar to the following (from another site):

(head(in ft) X GPM) / 10 = output in watts for a standard micro-hydro unit. So (10 (ft) X 100 GPM)/10= 100 watts. And with 1000 gallons this will last 10 minutes. 100 ft x 100 GPM = 1kVA which is about what an average US house needs. 100 GPM X 60 min X 24 hours = 144000 gallons per day.

or

In very rough numbers, a 1000-gallon tank 100 feet high could store about 3-4 kwh