Engineering help/ waterwheel

[wagspe208]

Yea, I know.... idiotic but here goes. I have a lake with a dam (duh). The dam height is 29', the water dept is 26'. On the other side of the dam is a 29' drop (duh again).
So, picture a valley, a dam in it 29' tall and the valley continues. SO, I was thinking off using an old fashioned style water wheel to drive a generator.
The waterwheel could be any size (so long as I can fab it and move it), but I would like to stay in the under 10' range if possible. There is an 8" drain in the dam, so this water could go up to water wheel height. (which will still be a 10' drop or so).
My question is how many gpm would I need/ or how many gallons per bucket would I need?
I would like to drive a dc generator and charge batteries. This would allow me to not run the wheel all the time. Any suggestions, or just crazy?

Wags

Oh, I was thinking of using a truck rearend for the bearing/ drive setup. I would build the waterwheel on one side of the rearend. On the other side I could use a rim/ pulley and belt to drive the gen or use the yolk of the rear end as a PTO output. Bearings sealed, no maintenance then.

[Apogee]

If I were you, I'd be looking at a Francis turbine or a Pelton wheel.  With 50' of head, a 2" line would have a fair amount of pressure if you located it at the bottom of the canyon.  I would think that you'd not drain your reservoir too quickly and it would charge your batteries very nicely.

It would be interesting to look at turbo chargers to see if one could be adapted into a mini-francis turbine.  If one could figure out how to keep the bearings sealed, it would likely work.

http://en.wikipedia.org/wiki/Francis_turbine

Just my $.02,

Steve

[KeithO]

You will need to measure your flow to get some real numbers to work with,
Bucket ,weir etc methods are on the net

Here is a link for flow using pipe size and head

http://www.calctool.org/CALC/eng/civil/hazen-williams_g

And one for water wheel power output

http://www.waterwheelplace.com/water_wheel_electricity.html

I'm building a wheel myself , but its mainly because I have little head to play with and I really like water wheels.
Your diff idea with the pinion drive has worked for others in the past but it will need to be strong as a 10 ft x 2 ft in 5mm steel is going to be way over a ton without water in it.

But at 29 ft you have many more turbine options ,  Pelton (double wheel probably) , turgo or even propellor in pipe, like a fixed pitch Kaplan

cheers
Keith

[wagspe208]

I think a 1 ton truck rear end will do fine. Hell, my dually can have 5000#+ on them plus truck weight. But I agree it will take a tough rear end.

I had not thought abbout a turbine. I won't have 29' of head as the valley is relatively flat. But I have 26' of water depth, so I'd have that minus turbine height.
How reliable are they? I want a plug and play. (meaning not break down every day)
Also flow will be regulated as it probably will not be a constant flow. I will have a shutoff valve. But, it is a 15 acre lake. Raising and dropping the water level 1' is a bunch of dam water. Have the calculation at home. And it will be an 8" feed pipe, but necked down for something easier to work with. 
I have hundreds of acres of runoff, so if/ when it rains, no problem. Also I have a spring that feeds it.
Thanks

Wags

[wagspe208]

Looks like these Pelton wheels used to exist. Anyone making them, or have any ideas where an old one is sitting?
Wags

[Derb]

Just a suggestion - run a 10 ft overshot wheel and use a smart drive permanant magnet generator geared up 2 to 1 ratio or similar with belt drive. These generators pump it out at very low revs. Kiss principle and cheap. cheers.

[wagspe208]

This is what I was thinking of. Seems easy enough.
How many watts does it put out? What does it power.. however you want to put it.
Wags

[Derb]

Hi Boss. Havnt been able to place full load on mine yet but blows 3 x 55w halogen headlamp bulbs on 18v battery drill on low speed! 12v is roughly 180 rpm. If I short out the DC conductors after the bridge rectifiers, it is damn hard to turn over by hand. It puts out serious energy at very low revs. If you are not able to get your hands on one of these washing machine motors, they are available over the net at a good price as a kitset. Have a troll on google. If you have no luck, I will flick you the website address when I am home. Cheers.

[wagspe208]

Hmmm... maybe I need to put the horse before the cart.
How much kw to I need to run my little house? I know... just say a standard 1500 sf house. And how much energy can I store in batteries?
Meaning I can't run my ac off it I assume?
A 10' water wheel better put out more than 150watts. 
If not, I'm barking up the wrong tree.
Or in comparison... a 10kw windmill is a big piece, but powered only by wind. I'd think water weight and torque would be way up there.
Thanks
Wags

[wagspe208]

Oh, and I've just started looking into "micro hydro". So, all the terms are new as well as places/ sources for info/ purchasing.
Thanks
Wags

[Derb]

Hi Boss. If you cant get 800 - 900 watts out of these units would have to be something wrong. Cheers.

[wagspe208]

Wow, this seems amazingly low. Maybe my perspective is off. My little Honda generator will put out 2000 watts. I know more rpms, but way less torque. A 10' wheel will have a huge amount of torque... yes? Little HP due to rpm though.
Wags

[Tom Reed]

While that does seem small, it is generated 24/7. At 900w that will give you 21.6 kw per day. We get by fine in our off-grid system at around 14 kw per day. I think the average US household uses around 15 kw per day. You probably will need to store this power in batteries to handle large power demands. What kind of load do you need to support?

[wagspe208]

This is in the future, so no load requirements yet.
I assume the 900 watt is per hour. So, 900 w x 24 hours = the 21.6 KWH. Hmm... seems obvious now. HA! I was struggling with the KWH thing for some reason. Or did not properly associate time with the 900 watt output.
In my current house I use as little as 735 KWH a month. I have used as much as 1835 KWH, but that was with all ac's running and 3 weeks of 90 to 100* days. ....SO... it seems as the 21.6 KWH x 30 days= 648 KWH? Right??
So, with some attention I could run on this for the light usage months anyway.
The new place will be much more energy efficient, and I won't be running a shop out of it. That uses a lot. 5 hp air compressor, lights, ac, equipment, etc.
Wags

[Tom Reed]

The nice thing about a battery bank is that the hydro power can be supplemented with PV or wind to make up the difference.