# Water turbine?

Discussion in 'Renewable Energy' started by b.james, Apr 4, 2015.

1. ### b.jamesMember

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Has anyone seen a shed setup with gutters that feed rainwater into a tank . The tank is sat on top of and floating in another and able to slide up and down inside it as the water is pressured out through a turbine producing power . A device ensures that the top tank feeds into the bottom tank keeping the bottom tank at the same level until the top tank runs dry when everything stops and awaits rain . The top tank is still available for drinking water. The next tank after the turbine is lower again and is available for drinking water and normal usage .. So three tanks . Middle one under pressure driving turbine and can also be used for water supply in an emergency

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2. ### alec_tWell-Known MemberMost Helpful Member

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Nice idea, but have you done the maths to see how much energy you could expect to harness? Do you live in a high-rainfall location?

3. ### cowboybobWell-Known MemberMost Helpful Member

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This calculator (http://www.powerspout.com/advanced-calculator/) will at least give you an idea of the feasibility of your idea.

Assuming a Standard Shed Roof (SSR) area of 144 sq. ft., and a (realistic) rainfall rate of 0.1'/min, I get 8.9gal/min (using http://www.metric-conversions.org/volume/cubic-feet-to-us-liquid-gallons.htm).

Using this calculator (http://www.powerspout.com/advanced-calculator/), 89 gal/min with an 9.8' head gives a result (using the PLT HP unit) of 2W.

There are other suppliers, of course, but I consider this device probably about average.

I should say that I have played with this concept before and was largely disappointed with the results. Maybe in Seattle this might work, but not in my neck of the woods (annual rainfall of 52").

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5. ### Nigel GoodwinSuper ModeratorMost Helpful Member

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'Standard'? - that would be a HUGE shed over here

Normal sheds are 8' by 6'

6. ### cowboybobWell-Known MemberMost Helpful Member

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True. I sort of made up the SSR "standard", primarily to help with the math: easier to get to cubic feet, then gallons (you know how we, on this side of the pond, just don't like metric ...).

7. ### Nigel GoodwinSuper ModeratorMost Helpful Member

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What makes you thing we do over here?

I buy beer by the pint, meat by the pound, and measure my car's consumption in miles per gallon

8. ### b.jamesMember

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I get about 6 meters of rain per year and my shed is 9 meters by 18 meters .Think of a meter as a yard and 3 inches

9. ### alec_tWell-Known MemberMost Helpful Member

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What size tanks do you envisage, and what head of water will be available to drive the turbine?

10. ### JimBSuper ModeratorMost Helpful Member

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I think of a meter as something for measuring stuff.

I think of a metre as 3 feet, 3 and three-quarter inches. Edit Should be 3ft 3 and 3/8 inches (39.37 inches)

JimB

(PS, the devil made me say it!)

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11. ### cowboybobWell-Known MemberMost Helpful Member

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Oops. And I've been to England. That's sad on my part...

OK.

So, in your example, with ≈1470sq.ft. of collector surface and ≈0.65" (on average, 956 cubic feet of water) of rain/day, you'd collect ≈7166 gallons of water per day, or ≈5 gallons/minute. For the sake of the calculator below, roof height is 9.8 feet.

Then let's say you have a 2", 10' tall vertical piping system from the roof level (assuming 9.8') water gathering conduit/storage to the power turbine (use this calc: http://www.calctool.org/CALC/eng/civil/hazen-williams_g). A 2" pipe (gravity flow only) can handle ≈40 gal/min., allowing for an ≈800% increase in rainfall rate.

From this "PowerSpout" generator calculator (http://www.powerspout.com/advanced-calculator/), this 1 day's rainfall would produce about 24W per day.

For the year, total production would be ≈365Wh per year.

<EDIT> Water flow rate through a 2" pipe by gravity only from this chart: http://www.monsterfishkeepers.com/forums/archive/index.php/t-205645.html

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12. ### tcmtechWell-Known MemberMost Helpful Member

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Ah the downside of water based power.

Unless you have a huge volume of fast flowing water or a high elevation change or moderate combination of both it's rarely practical for much of anything.

I have a good flowing stream within 50 feet of my house that runs at least 1000 - 2000 GPM most of the spring and summer and to be honest given the small elevation change I could maybe tap it for a few hundred watts at best with a dam the 5 - 6 feet of head I could make where I am at.

13. ### b.jamesMember

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Hey thats inportant to someone who regularly converts in his head. So its 1 meter = 3 foot 4inches more appropriately or 3 1/3rd feet.
But 1 meter equals
cm 100
mm 1000
km 0.001
ft 3.28084
in 39.3701

3.28 feet is pretty close to 3 foot 3 and 3/4 inches
So Ill work on 3 foot 4 inches in future

I thought I had seen a scheme on a web site from India somewhere where it was being used on a daily basis but I could not find it . I have two 22000 litre tanks that are always full and when it rains the gutters can't take it . The gully erosion is deep here and the rivers run full of mud to the great barrier reef so any man made pollution or errosion kills the reef. Sad but you can say its gone . Nothing will stop the fertiliser from bananas , sugar cane and tourist excrement in time now.

If you were planning a looksee go to the Caribean instead. Its a much better experience . I went there about 6 years ago. The coral was still alive and colourful Here its white and mostly dying

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14. ### b.jamesMember

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The other consequential observation in my case is I could run the water down a slope behind the shed . Its about a 300 ft drop and the power could get back up OK but the water would be lost.

I'm also considering the weight of the inner middle tank if it were made of concrete as my second two are .I suppose I would have to seal the sides somehow to get the benefit from that as pressure in the outflow pipe.

15. ### JimBSuper ModeratorMost Helpful Member

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Please note an ERROR on MY PART !

One metre = 39.37 inches, so I should have said One metre = 3ft 3 and 3/8 inches. NOT 3ft 3 and 3/4 inches.

Mea Culpa, which as you all know is Latin for "I have screwed-up, chaps!"

JimB

16. ### Nigel GoodwinSuper ModeratorMost Helpful Member

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We delivered a washing machine a couple of years ago, to an address around the middle of this map:

Notice the streets in the middle are Cornmill Close and Mill Farm Close.

Presumably there was a water mill there years ago, and the house we went to was the left hand one of a semi-detached pair, and the spring that fed the mill was bang on the middle line of the two houses. So they installed a small turbine, and it provides a continuous 2KW shared bewteen the two houses. There wasn't a huge amount of water flow, but obviously vastly superior to occasional rain on a shed roof

17. ### alec_tWell-Known MemberMost Helpful Member

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It might benefit instantaneous power for a short period, but the water will be 'used up' quicker so it won't make any difference to the total amount of energy you can harvest in the long term. You are limited by the rainfall.

18. ### cowboybobWell-Known MemberMost Helpful Member

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As with any energy source, its energy density (and your method of conversion) determines its utility.

In your case, the total quantity of your possible water collection is the only determining factor for energy conversion. No amount of manipulation of the delivery (or storage) of that quantity will affect the total amount of energy that can be extracted.

As stated by others, your only option to increase energy production is to increase the total quantity of water captured.

19. ### picbitsWell-Known Member

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I'd put money on that using a solar cell which would be cheaper than a generator for the water generator project, you'd get more usable energy in a couple of days than with the water generator idea in a year.

20. ### Nigel GoodwinSuper ModeratorMost Helpful Member

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I totally agree - he's collecting almost no water at all, and then he's got no fall at all either - nothing times nothing equals nothing.

21. ### picbitsWell-Known Member

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Don't forget the mechanical to electrical losses on nothing ........