Pumped Hydro Storage

Steven LakeSteven Lake ✭✭Solar Expert Posts: 395 ✭✭

Saw this article today and it got me to wondering how scalable this would be, in terms of home usage. IE, the big boys pump all their extra energy from power plants and green technologies into large storage ponds that run on demand hydro power. Sure, it works in large scale with some losses, but it would be intriguing, at least to me, to have something like this at your house, or private property, albeit in small scale, to cover larger sustained swings in power demand, then during times when you're producing more than you need, such as during periods of low usage and high input, use a hydro storage method like this that can be called up on demand for those times when your demand is higher than your input, and your batteries would be ill capable of keeping up, or if they could it'd eat your supply to death. Not quick spikes, but stuff that lasts more than 30 seconds, or for times when sustained demand levels exceed a given amount over a set period of time, such as a 30 second "kick in" window so you're not cycling the system on and off all the time.

Anyways, I'm just thinking. I'm always looking for unique ways to expand or upsize what an off grid system can do by coming up with creative solutions to rather complex issues. Or even simple issues with no simple answer. :) Feel free to comment if you want. Otherwise I'm happy to leave this at me rambling. :P


  • Ken MarshKen Marsh ✭✭✭✭ Solar Expert Posts: 114 ✭✭✭✭
    Re: Pumped Hydro Storage

    Sure it is scalable but the scale factor is the cube of your storage facility dimensions.
    This means it has to be big.
    When you get small the returns diminish rapidly.

    Some time back, on this board someone proposed using a water tower.
    Now water towers are big, typically 30 of 40 ft diameter.
    But in figuring it out, it will store about the same amount of power as a L16 battery.
  • BB.BB. admin Super Moderators, Administrators Posts: 29,634 admin
    Re: Pumped Hydro Storage

    From earlier calculations on other threads:
    BB. wrote: »
    It is possible--but probably not practical... One would need a pretty large tank of water 100' in the air to store more energy than a 2-4 golf cart batteries...

    I believe they use "hydro" to recover energy in hilly areas for city water (at least I have read about it in our area).

    But that is not a cheap project to put many tons of water on a 100' tower.

    From another thread; 5,000 gallons (~20 tons of water) at ~47 feet elevation:
    BB. wrote: »
    You can use a site like this:


    To figure out how much power you can generate for 5,000 gallons of water:
    Gross Head x Flow x System Efficiency (in decimal equivalent) x C = Power (kW)
    C is a constant (the value is different in English and metric units).
    • 100 psi / 2.13 psi per foot * 1 cf/s * 0.55 turbine eff * 0.085 = 2.19 kWatt
    • 5,000 gallons * 1/7.48 gallons per cuft * 1/1cf per sec = 668 seconds = 11 minutes of power
    Looks like a lot of "work" for little "work"... 2kWatts for 11 minutes.

    A pair of 225 AH 6 volt Lead Acid Batteries:
    • 225 AH * 12 volts = 2,700 WH for batteries
    • 2,190 WH * 11min/60min per hour = 402 WH for above water system
    In this example, the batteries store 6.7x more energy than 5,000 gallons at 47 feet elevation.


    6.7 * 5,000 gallons of water = 33,500 gallons of water at a minimum of 47 foot elevation change will store about the equivalent amount of energy as 2 golf cart batteries.

    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • vtmapsvtmaps ✭✭✭✭ Solar Expert Posts: 3,738 ✭✭✭✭
    Re: Pumped Hydro Storage
    BB. wrote: »
    6.7 * 5,000 gallons of water = 33,500 gallons of water at a minimum of 47 foot elevation change will store about the equivalent amount of energy as 2 golf cart batteries.

    But you can drain your water tank more than 50%, you don't have to worry about sulfation, and the tank will outlast many batteries.

    On the other hand, its a lot easier to water your batteries than a 35,000 gallon tank :p

    4 X 235watt Samsung, Midnite ePanel, Outback VFX3524 FM60 & mate, 4 Interstate L16, trimetric, Honda eu2000i
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