Generator head vs homebrew

[(unknown)]

Hello everyone, first post here so please forgive any newbie questions

Lately i've gotten more concerned with the state and stability of the world, so i want to become a bit more self-sufficient. I've been researching generating your own power and want to use a compination of my creek and solar to power my home. I've found i can get a 12kw generator head for about the same cost as building a homebrew generator. My question would be, how useful is an induction generator for battery charging? The generator would have to spin at 1800 rpm to maintain the correct voltage/freq, but as far as i know, there isnt an easy way to regulate speed from a waterwheel. So i would run the 3 phase wire to my house and there use rectifiers to convert it to DC which i'll charge batteries with.

Thats the plan anyway. Does anyone see any problems with this setup? The gen is self-exciting, but will running it much slower than its rated rpm still work ok? I imagine i can spin it around 500 rpm with normal water flow. Sound good? or will i be better off with the homebrew perm magnet generator? (which i'll probably make eventually anyway)

My battery bank will be 48v since i already have some 48v inverters.

Thanks all,

Mike

[RogerAS]

Mike,

First of all we need to know how much water power you have to harvest. How much water? How far does it fall? Can you legally alter the streambed? Is it a constant flow? Details are our forte here. :-)

One needs to choose the generator/alternator based on some of the above info. A big overshot wheel can maintain a pretty good state of steady RPM if not overloaded. That's the deal, making a steady state (rpm wise) water powered source. I'd give a bunch for just a small spring to tap some power.

Diversion loads can be eliminated from an overshot. When the batteries get all they need just have a simple water cutoff to the wheel. (I'd want that shutoff feature anyway).

With nearly any type of water powered rotational machine generating your electrical power you'll need a gearing ratio of a given rate of some kind. Belts don't mind running with a little water on them. A countershaft to the protected gen/alt and bingo. (I assume you are not talking abut building an enclosed turbine). Either the AC gen head or an induction motor will have to spin pretty fast. While you can harvest a great deal of torque from a simple water wheel the chances of getting high rpm is another matter. Some type of gearing would be needed even for a lower RPM PM alternator.

So give us the details and the users here will bend over backwards to help.

[(unknown)]

Hi Roger, wow that was a fast reply

I'll do my best to add some detail to the situation. The creek doesn't have a tremendous amount of fall. maybe 5 feet of drop over 100 feet distance. Hopefully that wont be a show-stopper. The creek is about 2 foot deep, maybe as much as 6 feet in a heavy storm. There is a golf course about 2 miles upstream which has helped the flooding lately (they get all the flooding instead now) so the depth rarely changes, which is nice since i dont have to rescue our frightened horses from the ankle deep water they walked into

Anyway, back to the creek, flow is constant year round, never freezes over here in SC, and making a dam is an option to get more fall. I'm not sure about the rate of flow, but its definitly not sitting still. Its not a huge amount of water to work with, but I hope to make some use of it as its always there.

So what do you think? Do i have enough to work with, or should I put my efforts into

solar?

Also, the creek is in a valley probably at least 300 feet in elevation lower than my house and i had the idea of putting a large water holding tank at the top of the hill and use something to pump water up to the tank and use gravity and pressure to spin a water wheel at a higher velocity. My boss thinks that a ram pump might work in that situation.

Thanks again,

Mike

[WindHarvester]

You'll find a wealth of knowledge at this link.

http://www.otherpower.com/otherpower_hydro.html

Read and observe the folks here and you'll receive an Otherpower education that money can't buy ;-)

Welcome to the board,

Lonnie

[tecker]

If your going to use a self excited induction motor at lower than rated RPM forget it . Got to have the revs to as the rotor retains the flux for just an instant.

[The Crazy Noob]

if you don't plan on living off grid, then just plug the induciton motor into your wall outlet and feed back to the grid. You can make money this way! And you don't have the battery and invertor losses!

some more info: http://www.fieldlines.com/story/2006/7/2/8853/36057

[robl]

Mike

You've gotten lots of good responses here. I would add one small comment to your original post. It is pretty straight-forward to get 120/240VAC at 60HZ out of your hydro plant. You just need a decent electronic load diverter. You can search on this site or Google the wider world.  One of my neighbours runs lights and radio directly off our little water generator (1800 RPM 1HP self-excited three phase motor)

Good luck

Rob