super small hydro - is it possible

[omegaman66]

Is this possible.

I have a camp site that has a small creek running near it.   The idea is to generate small amounts of electricity and store in batteries so I will have electricity in small amounts when I happen to be there.

Small stream Big Problem.  The problem is the stream is very small unless it has recently rained.  It has a fairly constant year round flow aprox. equal to the flow you get when you fill up your tub.

So I need some type of very small water wheel that can turn fairly slowly and still generate enough electricity so that it will charge a 12 volt battery approximately 15 yards away.

Is this even possible dealing with such a small scale system?

[drdongle]

If you can dam it high up, say 100 ft above where you want to install the generator and batteries then you could possibly use something like Harris Hydro System. These use small volume, high pressure water to spin a turbine attached to an alternator.

Carpe Vigor

Dr.D

[RobD]

Go to a plumbing outlet and buy a few hundred feet of 1" black plastic pipe. It's pretty cheap. This will give you the head you need to make power. You'll need to make a small pelton wheel turbine to go with it also.

RobD

[omegaman66]

Unfortunately that is not possible.  Total drop on my land is only about 6 feet or so.  This is Southwest Mississippi not a mountain get away.  Basically I would need something that you will be able to run in your tub. If anyone can think of a way to harness the energy used while filling a tub then that is what I need.  And energy will only be used to power a light or two.

[drdongle]

Your situation sounds like mine, low volume and low head= no hydro power.

Carpe Vigor

Dr.D

[Ungrounded Lightning Rod]

Did you see the stuff I posted previously about using an intermittent siphon to produce bursts of high-volume flow from a continuous low-volume flow?  This looks like a suitable use for such a setup.

Or you could build a REALLY TINY genny using a "toy" motor, divert maybe half the stream through it, and run it continuously.

Some wheel designs are over 90% efficient.  So several tubs a day with six feet of head will give you a non-trivial amount of power over weeks.

[Dan M]

There's an easy formula (although I can't remember it) to calculate power from gpm and pressure.

If you've got bathtub filling flow rates, and 6 ft of head, then plug in the following:

Somewhere between 5-10 gpm for flow.

Around 3 psi for pressure (for ~6 ft of head).

This will give you a theoretical maximum if you extract ALL of the energy and it's still going to be a really small number of watts.

Can somebody remember that formula??

-Dan M

[omegaman66]

I am new to all of this so can you give me more specifics with regard to how the little toy generator would be rigged up?

I know those toy motors are designed to be powered, not power other things.

Didn't see you other post on intermittent burst did a quick search and it didn't pull it up.  Will look harder in a few minutes.  First going to look for info on "water current turbines"!

[elvin1949]

omegaman66

good evening,i know your situation [just like mine]

it can be done.

It is very low power- 1 to 1 1/2 amp's max at 12 volt.

but for lighting in a weekend camp that is enough.

 At the lower end of the stream put an old timey water wheel. you want a BREAST wheel [high water will just help it turn]an overshot wheel will stop turning in high water.

 go to the upper end of the stream,put a small dam

6 inch's is high enough.Build your slouch[mispelled]

out of split 4 inch plastic pipe that is split end to end.Run that from the dam to the wheel[1/3 of the way down from the top of the wheel].

 This will give you 10 rpm's if you are lucky [not much power]so you will have to gear up about 10 to 1 for 100 rpm's give or take [speed of rotation is a guess but close.

 Build your gennie like the brake rotor mill only

cheaper. I am using the .7 dia by .2 thick ceramic disk mag's and 28 awg wire. [1 lb spool of wire and 100 mag's 28 dollars delivered]

 Stack the mag's 2 deep this will give 48 mag's and coil's. wind the coil's for 7 volts, series 2 coils for 14 volts,paralell the 24 set's for your amp's.    12/2 romex to bat's you have light's.

have fun

later

elvin

ps    i am in west central louisiana, not many hills here . lot's of water no drop.

[Ungrounded Lightning Rod]

I am new to all of this so can you give me more specifics with regard to how the little toy generator would be rigged up?

You'd rig it to a little toy water wheel.  A Banki turbine would be ideal.  They can handle very low heads at extremely high efficiencies and have a hysterical power-to-volume ratio.

I know those toy motors are designed to be powered, not power other things.

A permanent magnet motor IS a magneto.  Apply power, get rotation.  Apply rotation, get power.  No hax necessary.

[LIPOVITAN D]

One way I have found to turn a reasonable flow without much water drop, is to place a couple of pieces of plasic or treated wood at 45 degrees (or what works best) to the direction of the water flow (dig them in or attach poles to them and force them in nice and deep) this way to can get quite high pressure, and then a little motor or alternator attached to a water wheel will do fine. It is much more effecient than many smaller generators and much cheaper, and the planks provide a useful mounting place for the generator.

[Dan M]

I found the formula.

Power (watts) = pressure (gpm) x flow rate (gpm) / 2.3

so lets say 10 gpm and 3 psi (based on your description).

power = 13 watts

Let's assume your mechanism (water wheel), and generator are each 75% efficient.

This leaves an average of 13 x (.75) x (.75) = 7w of available power (small but more than I thought at first).

7w x 24 hours x 7 = 1.1 kw hr / week

for a 12v (charging at 12-14v) battery this is 80 - 90 amp hours per week. (which is also more than I thought it would be).

Have Fun,

-Dan M.

[TomW]

omegaman66;

I have said this before but I will say it again:

Many things are possible.

Very few things are practical.

You can probably make more power by hand cranking a real generator for few minutes than you will see from a 6 foot drop and a trickle in a day.

Note I did not say it wont work.

Around here that kind of flow would be referred to as a spring or a seep, not a creek.

Anyway while it might actually work at some level because there is some power available in any moving water but there are other options that are probably much better in that situation. You either need a good fall or good flow to do hydro well. Sounds like you have neither. You could calculate the power available if you gave solid numbers on fall and flow rate but about like filling your tub is too vague to plug in to any formulas.

Good luck if you try.

T

[Ungrounded Lightning Rod]

so lets say 10 gpm and 3 psi (based on your description).

power = 13 watts

Forget the "toy motor".  An automotive heater-fan blower sounds about right for that guesstimate.

Let's assume your mechanism (water wheel), and generator are each 75% efficient.

A homemade Banki turbine might be 60-70, a PM motor probably in the 85-90.  Call it six watts.  Still no slouch.

[omegaman66]

Thanks to EVERYONE for the very valuable input.

Clarification.  6 foot is probably the total drop.  2 to maybe 3 feet is the most I will be able to get.

*I realize when 100 foot of head was mentioned that they didn't realize my situation.  I would need about (literally) 150 miles of pipe before I would get 100 ft. of head.  My stream elevation is about 150 feet and I am about 300 miles from the coast.

*Right on calling it a seep by the flow.  The flow is (without rain) about 5 to 10 gallons a minute.  Even in drought the flow doesn't slow noticably.  But the creek bed it is in is quite large and sandy.  If it was smaller it would be called a ditch (here) but it is pretty not ugly and when it rains hard the water flow gets up to something on the order of the Mississippi River!

*Looks like solar will be the best way to go but will look into it alittle more.  Will check to see if I can get enough from this flow mathematically.

Thanks everyone for being so helpful.

 

[patty3]

If you get 5 to 10 gpm, and water weighs 10lbs to the gallon. How many ft/lbs or in/lbs of torque could you get with a bucket type waterwheel and would it be enough to gear up to a speed that would run a small PMG?

[sh123469]

I thought water weighed 8 lbs. per gallon.

But the problem here is that there is no head.  He only has ~6ft. of drop across his land.  From one end to the other, you might be able to achieve a 4ft overshot wheel.  Not a lot of torque there especially at the low flow rates. At 10 gpm, that's only 80 lbs of water per minute.

[Muffloj]

    Keep it up you might get to use a little power from your drainage ditch. But you might wanna think hard on it you may have already used more energy researching it than it will ever produce.

   a gallon weighs 8.35lbs

   

[JYL]

It depend were you live.

An Imperial gallon (168 once) is 10.5 pound.

An American gallon is (128 once) or about 8 pound.

Now, in both system, a pound is 16 onces.