# Hyrdo Energy From a Pond??? Input on another crazy idea.

Discussion in 'Homesteading Questions' started by SouthernThunder, Jun 18, 2005.

1. ### SouthernThunderWell-Known Member

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I have been looking into alternative energy recently for many reasons. (The main one is I don't want to sign an easement to the utility company here) Anyway the thing that seems to aggravate me the most out of all these systems is that they ALL rely on batteries.

I hate batteries. They have two very serious drawbacks as far as I am concerned. 1) They are VERY expensive to purchase initially. 2) If you're lucky, they will last you 7 years, which leads us back to #1.

So I have been looking for another way to store the energy produced during a good sunny and windy day. The only way I could think of was in the form of potential energy. That is to say... a pond. Here's what I would like to do.

I would have a large storage pond on top of a hill. About 150-200 feet below this hill I would have another storage pond. I would like to run water from the high hill 150-200ft down a tube to a pelton wheel generator at the bottom. Then the water would run off into the lower storage pond. During the day and in times of wind I would use solar and wind powered pumps to pump the water from the lower pond back to the high pond. This higher pond would in effect, be my battery. Excess power not used by the home would be ran to an electric pump to push more water back to the high pond thus helping somewhat in the efficiency of the system.

Having said that, I realize this is an incredibly inefficient system but once its up and running it would be a lot more cost effective than having to buy and maintain a battery bank. (which I will never do!)

Now admittedly, I have had some problems in figuring some of this out because my math is a little rusty. All the formulas I have found are for running streams or rivers and nothing takes into consideration the PSI of a mass of water. How would I go about calculating how much water (gpm) I would need to generate 5kw with a head of 150-200ft starting with a stationary pool of water? My main fear is that it will require a larger gpm to power than my return pumps can recover during times of sun/wind.

Lastly, is there anyway that I can increase the power output of a pelton wheel by changing the velocity or pressure of the water in some way? Would a 4 inch pipe leading 200 feet to the jet be better than a 1 inch pipe?

2. ### DrippingSpringsIn Remembrance

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mini hydro turbines are good for this use. I know someone who has tried pretty close to what you are doing and was reasonably successful. He had a good sozed pond that had a natural spring feeding it and he had a pipe situated about four ft underwater to drain from. He charged batteries with his though.

3. ### DrippingSpringsIn Remembrance

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BTW I have often wonderd if there were someway that a person could put a mini hydro turbine of similar thing in the water line between your house and the meter. That way every time you are turning water on to shower, wash clothes water animals etc it is essentially spinning the turbine or wheel to produce electricity. The pressure would insure a good spin I would think.

4. ### fordyWell-Known Member

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...............ST , My perspective , (1) you have alot more Sun\Wind than you do Rain . So , your MAIn source of power should be predicated upon a Solar<>Wind based system . Secondary , to this system , Hydrogen power will also provide power . BUT , I would only count on this system when it rains . Now , you just aren't going to beable to achieve very much UNLess , of course you had a spring flowing 24\7, and you don't , so Batteries are a Requisite part of the System . Battery technology has progressed to the point that they are good for 20 years or so , IF you install one of those Controllers that Monitors the state of charge very accurately . And , it is possible for the monitor to Desulfate the Battery bank as often as necessary based upon the "state of charge" . Whatever your decision Please keep Us\Me informed as I very well maybe faced with this same scenerio within the Next couple of years or SO . All , in all , it would be cheaper to just pay the Utility to run the power up too your Casa but I understand that you despise having to jump thru their hoop as much as Ido . Good luck on having to choose between Unreasonable Choices , fordy..

5. ### Ken ScharabokIn Remembrance

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What you are proposing sounds very close to the concept of perputual motion. I am about 99.999999999999999% it won't work. You will require more energy to refill the upper pond that what can be produced from it.

6. ### palaniWell-Known Member

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Another alternative - microturbine generators. You could use LP or natural gas if available, generate electricity at \$.035 - \$.085 per kwhr. In order to be cost effective consider co-generation, where you would use the residual heat from the generator to heat water that could then be used to keep a greenhouse at a reasonable temperature overnite or to heat a house. You might use the electricity generated to pump water up to your higher pond.

check out http://www.drykiln2000.com/ or do a search on any search engine for microturbine generators. These things are going to come down in price and be mighty popular in the next several years.

7. ### WagsWell-Known MemberSupporter

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8. ### to live freeWell-Known Member

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you can use a water ram to return water to the upper storage pond. i am planning on build a system like this as well, only thing that is a draw back for you(i have a stream to keep my pond full) is a constant source of water. evaperation will be a problem if there is no constant supply of water, or a refreshing from time to time. if you do not use electricty constantly then you can use solar,or wind to pump water back to restart the cycle, but if you can live with electricity for day or two pumping should not be a problem if you sorce of supply for water is not a constant.

9. ### texicanWell-Known Member

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Hi SouthernThunder

been there, thought about it, backed out gracefully.

1st off, you don't have to spend a fortune on batteries...if you've went to the trouble of paying for solar panels, you'll have a pretty good chunk of change tied up no matter how small your system... You can easily pick up golf cart deep cycle batteries for under \$50 each. Need a minimum of two, four is better.

Your using excess power to pump water uphill will eat many amps...250' uphill would require 120lbs pressure (2' of elevation will give you 1 lb pressure) which will take a pretty stout pump (which will cost many multiples of a small battery system).

And then you only get a small percentage of the energy returned to you through a pelton wheel...your looking at many thousands for something in the 5kw range...10 years ago I was looking at the smallest systems, and they started ~600.

To turn a 5kw pelton will require a huge volume of water. I understand you want to use the excess power in a kinetic energy storage system using water, and not a 'perpetual energy machine'. You'd need a pretty good size pond, above and below....are they already built??? that can be thousands if you have to get em dug...and the water HAS to be filtered, or your pump and pelton will wear out pretty quickly.

Your efficiency I would guess would be in the single digits. Pump, piping, pelton generator = >BIG MONEY!!!

What I did was to simply oversize my system, so I'd have about a three day cushion in my batteries...no sun for three days, no electricity...so each day I'd mentally monitor the sunshine...if it didn't shine, I'd cut back on my usage, two days of no sun, I'd cut back more (to try and extend my batteries to three or four 'extra days')... monitor the battery bank each morning and evening to see how much I could use that day or that night... never letting the batteries get below 50% capacity. These batteries would last me three years. \$200 for four batteries...cheap enough for me.

Looked at hydro, thinking my 8 acre, 30' deep pond would fill in my electrical shortages during the rainy season....when it rains, the hydro system would kick in, as excess water was going over the spillway (when it rains, solar panels don't work :no: ) I was looking at several thousand, for a sytem that would only work a few weeks out of the year...about that time grid electricity became available for half that, so I hooked up gladly......believe me, the romance wears thin when troubleshooting time hits....and there's no one's brain to pick but your own....

10. ### ponyboyNew Member

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A buddy of mine had a similar idea. Instead of using a windmill to make electricity he wanted to use it to pump air into a large underground storage tank. Then when wind stopped blowing or the sun stopped shinning he would use the air in the tank to turn a generator like the pelton wheel. He wasn't fond of batteries either.

ponyboy

11. ### rzrubekFlying Z

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Go here http://www.fieldlines.com/ and sign up and run your idea across them. What you propose would work, but the extra solar and windmills would cost way more than batteries. The people at fieldlines are very smart about this stuff.

12. ### texicanWell-Known Member

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On reflection, and don't take this the wrong way...

If you really really dislike batteries, I'd recommend forgetting about alternative energy...hydro, wind, or solar...because battery storage or grid tie-in are tried and true parts of the equation. Like a peanut butter and jelly sandwich without the peanut butter.

With unlimited funds and patience, yes, you could overcome the battery obstacle...or you could just use electricity during the day. Taking batteries out of the off the grid equation is the equivalent, imho, of hauling the water out of your lower pond in 5 gallon buckets, up the hill to your upper pond, to power your pelton wheels...

good luck

13. ### moopupsIn Remembrance

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I read an article a ways back about a western city doing just what your suggesting, they pumped water up with solar energy and took electricty from the downward flow of the water, the difference being that they used 5 power gathering stations all intermintiantly spaced in the flow path. The waters weight was captured to turn the 5 turbines, all with positive displacement. The water was in a closed system the entire downward path. I do not remember the cities name but may find it via google.

14. ### SouthernThunderWell-Known Member

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Holy Cow! Thanks for all the input folks! I have found some formulas on some micro turbine sites and they kind of confirm my worry that it is going to take a large flow rate to generate the amount of juice I want.

See if this info looks correct to you. ?

1HP is equal to 746watts.

So a 5kw genhead would require 6.7hp to turn it. (if it was 100% efficient)

6.7HP * 2178constant / 200ft head = 73 gpm (formula for gpm)

73gpm * 60min * 24 hours = 105,120 gallons per day

There are 7.48 gallons in one cubic foot of water so 105,120 gallons is

14,053 cubic feet.

For a 30 foot deep pond this would need to be about 234ft by 234ft. (for the ease of calculation, we're making the unlikely assumption that it is 30ft deep all the way around.)

234x234 is just a little bigger than a 1 acre pond.

So to generate 5 kw of electricity in one day I would have to drain out a 1 acre pond 200 feet down at a rate of 73 gpm. Now there is a VAST number of variables I am not taking into consideration here. Assuming that you use all 5kw all day long then you put nothing back into the system and have to find some way to refill the pond.

For what its worth, I don't see buying some solar panels the same as buying batteries because panels would not die out several times in my lifetime. Also, my plan was to use "air lift" pumps to move the water because they have no moving parts to wear, and can move sand and sludge occasionally without any damage. I can also make these cheaply myself. This is not a perpetual motion machine because I am constantly feeding energy into the system and only getting a fraction of it back. :waa: Just like a battery.

With proper wind and sunlight this could work. I would build a 6 acre pond to give me enough storage to run for 4 or 5 days without any sunlight or wind. I would run excess electricity back into a pump to return water so that the system is not totally wasteful. I would probably make the water release system a little smarter by making it sensitive to the electrical demands at any given time. (like one of those fancy Lincoln welders)

Unfortunately, as stated, I do not have a constant source of flowing water. If I did I would certainly go forward with this. At this time though, it doesn't seem very logical to do it the way I planned.

Fordy, I was unaware that batteries are now able to last up to 20 years. This is a reoccurring cost I could be a little more comfortable with. I figure maybe I replace them twice in my life time and hopefully somewhere along the way fuel cell technology will be improved. :haha: I will definatly keep you posted on where I wind up with this electrical issue.

Thanks again for the links and helpful comments folks. You guys are the greatest resources I have!

15. ### OregonsparkieWell-Known Member

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SouthernThunder,

Just remember 5000 watts(5kw) is not very much and the 5000 watts firgure is alot of times peak not continious..To put it simply, 5000 watts is equivelant to (2) standard car alternator(200 amps each). A 5kw generator is usually based on 120 volt not 240 volts. Most stoves run 240 volt and about 30 amps(7200 watts), of course you can run propane or natural gas but you will still be at the mercy of oil companies and an easement for the gas line.

Without batteries any unused electricity is lost..Look into other devices like the sterling engine or more efficient turbines than the pelton wheel. I seen some advertisment a while ago for a pump that could pump 20 feet uphill from a water source with a one foot drop. Dont know if it was for real or just some hype.

To research all the alternative energy sites would take a very long time but one idea can lead to another, and another... who knows you could come across the holy grail of energy generation...

16. ### OregonsparkieWell-Known Member

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Just had a nother thought that could be some what inexpensive depending on your knowledge base..

Use solar to heat water to steam and use the steam to pump your water.. Of course this is completely dependent on the sun but all things together, it helps make your idea work..

17. ### DarrenStill an :censored:

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I'm in a similar situation. I have a pond and a rear round stream about sixty foot below that in elevation. The pond is about 300' below the ridge. I considered using sling pumps in the creek to deliver water to a series of rams gradually filling a pond on the ridge. The outflow from the current pond would also be fed to a generator. When I looked at how much water would be required to generate the needed power, it wasn't feasible unless I built a reservoir and only used it for brief periods due to the inability to fill it fast enough.

What will work if you go with either wind or solar and don't like batteries is a flywheel energy storage device. Unlike batteries, flywheel energy storage is relatively new and is certain to improve in performance with advancements in materials science. Costs should decrease as production increases when they replace batteries in applications such as central telephone offices.

18. ### palaniWell-Known Member

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SouthernThunder

You might want to double check your calculations. 14053 cubic feet for a 2 foot deep pond would be a square 83 feet on a side.

19. ### SouthernThunderWell-Known Member

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Thats why I posted my calculations, cause I am not good at calculations!

I did the figure for a 30 foot deep pond. So 14053 / 30 is 468. I divided this by 2 to get my figure of 231.
Hmm... now looking back over it I can see why its wrong (dealing with cubes) but Im not sure how to arive at the correct answer. Care to spell it out for poor ol' me? :bash:

Hey BTW, I am looking into those solar steam powered generators right now... Good idea but I'm kinda concerned that nobody has a working model capable of supporting a home. I did find a site that had a picture of one a farmer built that focused sunlight into water and had a 100 gallon boiler. The whole system was pumping 130 gallons of water per minute for his stock. This was done back in the early 1900s I think.

Flywheel energy storage is a new one for me... gonna have to look into that.

20. ### SouthernThunderWell-Known Member

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Ok. I believe this is correct.

30ft x 22ft x 22ft would contain the amount of water needed to power a 5kwh genhead for a 24 hour period. Flowing 73 gpm with a head of 200 ft.

If this is the case, then things look a lot more feasble.

A square pond 30ft deep, 49ft x 49ft would yeild enough energy for a 5 day run.

Thats 538,784 gallons for 5 days or 107,756 per day. Does this sound right??? That actually doesnt seem like that much water compaired to what I was expecting and my previous miscalculations.