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george357
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join:2009-09-18
Weaverville, NC
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Need advice on a small water-powered electrical system?

A friend currently lives in a small cabin with no electricity and no ability to get it for now. We have been talking about implementing a water-wheel type generator to run some basic electrical components. Currently, we are looking at powering a small string of LED lights, an average size TV, and hopefully a refrigerator. The idea is to build a bank of 12-volt deep-cycle batteries to run an inverter for the components. The water-wheel would maintain charge on the batteries. I believe that the first step would be to determine the max power (amps/watts) the equipment would draw then base the number of batteries from that. After this I guess the generator size could be determined. Once the correct generator is found we would have to figure the flow rate of the water and the gear reductions between the wheel and generator for proper output. Does this sound like the correct procedure to accomplish this project? Any ideas or comments to make this more effective? Any help would be appreciated.
--
malo periculosam libertatem quam quietum servitium

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ropeguru
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join:2001-01-25
Mechanicsville, VA
Why not solar and/or wind turbine? The TV would be the biggest draw as you could get a propane powered fridge like they have in motor homes.

Not sure of the size you might need though.


george357
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said by ropeguru:

Why not solar and/or wind turbine? The TV would be the biggest draw as you could get a propane powered fridge like they have in motor homes.

Not sure of the size you might need though.

To the best of my knowledge the water system would be cheaper than the solar and I am not sure there is enough wind in the area on average to justify a windmill.
He is hoping to use the fridge he already has and not have to add the expense of propane. He is wanting to do this as cheaply as possible because of his current financial situation.
--
malo periculosam libertatem quam quietum servitium

Cancer Cures Are Just A Crunch Away


SparkChaser
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reply to george357
A lot will depend if you have enough flow and head (fall).

Take a look at these sites

»otherpower.com/otherpower_hydro.html

»www.waterwheelfactory.com/


george357
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Weaverville, NC
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Thanks for the links! We are trying to determine head and flow as well as the other aspects. Just not sure which would be the best factor to figure out first.


cowboyro
Premium
join:2000-10-11
Shelton, CT
reply to george357
Do some math regarding the flow * drop * efficiency of the water turbine.
A TV will use some 200W assuming it's CRT. Fridge you're looking at 100W almost continuous. You might be able to start a very small one with an inverter, provided that the inverter is capable of 1000W.
So you're looking at a minimum of 100W continuous, maybe 400W for 4hrs/day (throwing numbers). 3.6kWh/day. With a 80% efficiency (let's be realistic) you need 4.5kWh from batteries, maybe 6kWh/day supplied by the turbine. That's 250W continuous. Typical generator efficiency is 60% -> turbine must provide some 400W
Sine you're not going to have a super-efficient turbine (90%+) I would guesstimate 70%.
P=0.7*1000[kg/m^3]*9.8*h*q where h is the drop [m] and q is the flow [m^3/s]
400 = 6860*h*q -> h*q = 0.058
You need 58L/sec falling from 1m to get the power.


george357
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said by cowboyro:

Do some math regarding the flow * drop * efficiency of the water turbine.
A TV will use some 200W assuming it's CRT. Fridge you're looking at 100W almost continuous. You might be able to start a very small one with an inverter, provided that the inverter is capable of 1000W.
So you're looking at a minimum of 100W continuous, maybe 400W for 4hrs/day (throwing numbers). 3.6kWh/day. With a 80% efficiency (let's be realistic) you need 4.5kWh from batteries, maybe 6kWh/day supplied by the turbine. That's 250W continuous. Typical generator efficiency is 60% -> turbine must provide some 400W
Sine you're not going to have a super-efficient turbine (90%+) I would guesstimate 70%.
P=0.7*1000[kg/m^3]*9.8*h*q where h is the drop [m] and q is the flow [m^3/s]
400 = 6860*h*q -> h*q = 0.058
You need 58L/sec falling from 1m to get the power.

Thanks for the info! The TV is either LCD or Plasma will clarify asap, with 100w continuous to the fridge what would u think that the surge would be for start-up of the compressor?

EDIT: Additional information.
We were considering an older automotive generator (not alternator) as the charging source. Would this be feasible or would a purpose designed generator be a better choice.

--
malo periculosam libertatem quam quietum servitium

Cancer Cures Are Just A Crunch Away


shdesigns
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1 recommendation

Why an old auto generator? My Willys had one. After it fried itself the second time (stuck regulator relay) I swapped it for an alternator and never had problems again.

You can get "1-wire" alternators relatively cheap. I picked up a 200 amp one for just under $100. Included the internal regulator. Just connect to battery and provide +12V to the reg.

If you are just charging a 12V batt, that is all you need.
--
Scott Henion

Embedded Systems Consultant,
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UHF
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reply to george357
said by george357:

The TV is either LCD or Plasma

If it's plasma, good luck. Those things are power hogs.


george357
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reply to shdesigns
said by shdesigns:

Why an old auto generator? My Willys had one. After it fried itself the second time (stuck regulator relay) I swapped it for an alternator and never had problems again.

You can get "1-wire" alternators relatively cheap. I picked up a 200 amp one for just under $100. Included the internal regulator. Just connect to battery and provide +12V to the reg.

If you are just charging a 12V batt, that is all you need.

Just figured that an older generator would be better suited to this application thinking it would require less RPM's to produce the necessary charge when compared to a newer alternator.

said by UHF:

If it's plasma, good luck. Those things are power hogs.

Yeah I know, I have a 50" (though his is smaller 32"-40") and that can pose an issue. I am 75% certain that its an LCD but included the plasma aspect just in case.
--
malo periculosam libertatem quam quietum servitium

Cancer Cures Are Just A Crunch Away


cowboyro
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join:2000-10-11
Shelton, CT
reply to george357
said by george357:

what would u think that the surge would be for start-up of the compressor?

In the 1000W+ range. From what I see in a quick search it can be as high as 20-30A (2400-3600VA) for a fraction of a second. I've been unable to start either of my 2 refrigerators on a 900VA UPS, it would shut down instantly. You made me curious, if I have time tonight I'll try to record on the oscilloscope...


SparkChaser
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reply to shdesigns
said by shdesigns:

You can get "1-wire" alternators relatively cheap. I picked up a 200 amp one for just under $100. Included the internal regulator. Just connect to battery and provide +12V to the reg.

If you are just charging a 12V batt, that is all you need.

+1 on the alternator


drjim
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And IIRC, when Chrysler was the first to start putting alternators on cars, they made quite a big deal about how it would keep the battery charged even idling at night with the lights on.
Probably moot in this case, as you can change the drive ratio to get whatecer speed you need with the water flow you have.
--
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shdesigns
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reply to george357
said by george357:

Just figured that an older generator would be better suited to this application thinking it would require less RPM's to produce the necessary charge when compared to a newer alternator.

More the other way around. My Willys could not charge at idle with the lights on (I had added tail lights.) The alternator had no problem.

Generators are unreliable, brushes wear and they would have mechanical regulators with relays.

I have yet to see a car that cant do a good charge at idle with an alternator.
--
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DesertRats
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join:2003-11-23
Santa Clarita, CA
reply to george357
George357,
You may want to take a look at a magazine called "Home Power" www.homepower.com
They cover Hydro, Solar, and Wind Designing and Building.
I have seen them cover many hydro projects in the past.
My interests are in solar so I have not followed the hydro projects.
As I recall they have a forum where you can ask questions. Don't hold me to the forum part.
I see on the web site a tab for "Microhydro Power"
That may have some info that could help you.

lutful
... of ideas
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Ottawa, ON
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reply to george357
said by george357:

... After this I guess the generator size could be determined. Once the correct generator is found we would have to figure the flow rate of the water and the gear reductions between the wheel and generator for proper output. Does this sound like the correct procedure to accomplish this project?

Choosing the correct type of turbine for the actual water energy source is extremely important. Your friend he may have a weak stream of water running down a very high hill or a very fast moving stream but just a few feet drop within his property limits.

said by george357:

Any ideas or comments to make this more effective? Any help would be appreciated.

Please describe the actual stream with a few photos and/or co-ordinates so we can check using Google Earth.

Based on your friend's needs, the generator could be 2KW to 5KW range. It is better to oversize the generator (if the energy source and turbine specs allow that) because of the motor in the fridge and because later on he may want a computer and wireless or satellite internet.


george357
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reply to george357
said by cowboyro:

In the 1000W+ range. From what I see in a quick search it can be as high as 20-30A (2400-3600VA) for a fraction of a second. I've been unable to start either of my 2 refrigerators on a 900VA UPS, it would shut down instantly. You made me curious, if I have time tonight I'll try to record on the oscilloscope...

Thanks, that could be interesting to see.

said by SparkChaser:

+1 on the alternator

said by drjim:

And IIRC, when Chrysler was the first to start putting alternators on cars, they made quite a big deal about how it would keep the battery charged even idling at night with the lights on.
Probably moot in this case, as you can change the drive ratio to get whatecer speed you need with the water flow you have.

said by shdesigns:

More the other way around. My Willys could not charge at idle with the lights on (I had added tail lights.) The alternator had no problem.

Generators are unreliable, brushes wear and they would have mechanical regulators with relays.

I have yet to see a car that cant do a good charge at idle with an alternator.

Ok, looks like we will use an alternator, thanks for the input!

said by DesertRats:

George357,
You may want to take a look at a magazine called "Home Power" www.homepower.com
They cover Hydro, Solar, and Wind Designing and Building.
I have seen them cover many hydro projects in the past.
My interests are in solar so I have not followed the hydro projects.
As I recall they have a forum where you can ask questions. Don't hold me to the forum part.
I see on the web site a tab for "Microhydro Power"
That may have some info that could help you.

Thanks for the info, I will look that site over and see what I can come up with.

said by lutful:

Please describe the actual stream with a few photos and/or co-ordinates so we can check using Google Earth.

Google earth is not likely to help as the pics aren't very detailed with no views of the stream (just so you can see what I mean the co-ordinates are: 35 degrees 48' 41.56" N x 82 degrees 51' 7.75" W). The stream is pretty small, about 18"-24" wide at the widest. It runs about 6"-10" deep average and does have a lot of fall, its pretty steep around here. My friend has the acreage to run several feet of pipe/trough to feed the wheel/turbine. I can try and get some pics later.
--
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Cancer Cures Are Just A Crunch Away


jrs8084
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Statesville, NC
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I certainly hope you meant feet and not inches for your stream measurements.


george357
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said by jrs8084:

I certainly hope you meant feet and not inches for your stream measurements.

No, the inches are an accurate guesstimate. We are hoping that the supply trough/pipe fall rate in combination with gearing of the alternator drive will be enough to supply the force needed.


SparkChaser
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said by george357:

said by jrs8084:

I certainly hope you meant feet and not inches for your stream measurements.

No, the inches are an accurate guesstimate. We are hoping that the supply trough/pipe fall rate in combination with gearing of the alternator drive will be enough to supply the force needed.

Let's hope the fall is enough to make up for the flow. Have you done any flow measurements, yet?

OT - Nice country down there. Used to have a relative that lived in Hickory and I traveled a bit there.
--
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cowboyro
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join:2000-10-11
Shelton, CT
reply to george357
said by george357:

The stream is pretty small, about 18"-24" wide at the widest. It runs about 6"-10" deep average and does have a lot of fall, its pretty steep around here. My friend has the acreage to run several feet of pipe/trough to feed the wheel/turbine. I can try and get some pics later.

That sounds awfully small.
Do a test first and see how long it takes to fill a big barrel in order to get an idea about what you can achieve.


cowboyro
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join:2000-10-11
Shelton, CT
reply to george357
said by george357:

We are hoping that the supply trough/pipe fall rate in combination with gearing of the alternator drive will be enough to supply the force needed.

It's all about power (energy/time), not force.
If the water doesn't have enough energy then no gearing will help.
You need to supply X watts of mechanical power to the alternator, plain and simple.


george357
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Weaverville, NC
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reply to SparkChaser
We have not done any flow tests as of yet, I guess that would be priority at this stage. I will see what we can come up with. Thanks everyone for all the info so far.

walta

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Saint Louis, MO
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Has this stream ever run dry?
Would it be possible to dam the stream and form a small lake?
Do you know the source of the stream?

Walta


george357
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said by walta:

Has this stream ever run dry?
Would it be possible to dam the stream and form a small lake?
Do you know the source of the stream?

Walta

The stream has not run dry to my knowledge, a small dam could be made but nothing large...it is a spring-fed stream.
--
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tschmidt
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Not to discourage you but when we purchased our property had visions harnessing our small stream for hydro power.

Looked great in the spring after snow melt but by August it slowed down to a trickle.

As cowboyro See Profile posted it is all about flow rate and head. Need a fair amount of both to make the project worthwhile.

In NC at least you don't have to worry about the stream freezing in winter.

/tom


cowboyro
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join:2000-10-11
Shelton, CT
reply to george357
OK, so here is the startup of my "normal" fridge from the basement.


The reference is a ~1500W heater which actually took 11.2A, so in the 1300W range. As you can see the fridge takes up to 1500VA for about 250ms, although I've noticed occasional higher peaks while some are lower... so even a smaller fridge may still suck some 1500VA at startup. I wouldn't even dare put a fridge on an inverter that can't reliably give peaks of 2000W+, as it takes a single random surge to end up with spoiled food.


drjim
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Pretty cool.....

What did you use for a current probe?
--
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cowboyro
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Shelton, CT
said by drjim:

Pretty cool.....

What did you use for a current probe?

A piece of wire shunt.


SparkChaser
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said by cowboyro:

A piece of wire shunt.

Good keep it technical

I have an old 200A meter shunt I use for stuff like that.