Want to build one of those old-style water wheels powered by a waterfall. Is there a more efficient way than the ones that were around since the start of the industrial revolution?

  • look for Banky Turbine, they are efficient and comparativly easy to build.
    – mart
    Commented Oct 1, 2013 at 8:58
  • vortexhydroenergy.com - saw this from university of michigan - seems legit - thoughts? Commented Oct 1, 2013 at 21:18
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    Once you come up with a set of components you can ask specific design questions on Electronics SE.
    – sharptooth
    Commented Oct 10, 2013 at 7:08

3 Answers 3


I guess it depends on what you mean by "better".

The traditional way needs a pipe, the penstock, feeding as much clean water as possible from as high as possible directly onto a pelton turbine, which is connected to a generator.

The drawbacks are that the water must be as clean as possible and you should use all water for maximum efficiency. You also have to source a decent pelton turbine.

For the ecosystem of your stream/river, this setup usually prevents fish traveling past your power plant. It seems to be general permaculture knowledge that the nutrients, which get washed out into the sea, travel back up in the form of small snails, crayfish and the like, which, it is believed, play an important part in keeping a land healthy.

A fairly new (about 10 years) system is known under the cumbersome name "gravitation water vortex power plant", where water is fed into a pool tangential to the edge of the pool. The water forms a vortex, as in your bathtub, and blades are inserted into the vortex to slow down the rotation. The blades are connected to a generator and give you the electricity.

vortex power plant

The picture explains everything, but you can also watch it in action.

Since the water is fastest at the edges and slowest near the centre, fish and other freshwater creatures can travel past your power plant. (Also, not really applicable when you already have a waterfall, you don't need a large "head", i.e. a large difference in height.)

As a very rough estimate, a small stream (maybe 2-3 meters wide) can provide electricity for several households.

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    I thought the asker was talking about one of these: en.wikipedia.org/wiki/Water_wheel Commented Sep 26, 2013 at 11:06
  • @HighlyIrregular You're not alone. But the vortex solution seems more elegant and efficient. Commented Sep 26, 2013 at 14:37
  • @HighlyIrregular The water wheel has been around for much longer than the "start of the industrial revolution" (see the Wikipedia page you linked to).
    – Earthliŋ
    Commented Sep 26, 2013 at 15:01
  • @Earthling vortex thing looks really cool - i know water wheels were around for much longer than the industrial revolution - just wasn't used to generate electricity - Commented Sep 26, 2013 at 18:56
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    Do you have any sources that do a side-by side comparision with otheer turbine builds?
    – mart
    Commented Oct 1, 2013 at 8:57

The Banki Turnine is often mentioned in connection with small scale hydro and DIY projects, because it’s far easier to build than a Pelton turbine.

Ossberger, one major supplier, claim 80% efficiency for a small scale turbine over a wide range of flows – this will, of course, be lower for a home built one.

This document seems to contain detailed instructions for building on, including the welding of the turbine itself.

Disclaimer: I'm not in hydro and have never built such a system, so I can’t really vouch for it.

An additional possibility would be to use a hydrodynamic screw – working principle:
enter image description here

The German Wikipedia article states efficiencies of typically 70%, 90% is possible. Apparently, screws handle load changes and part load operation very well, but are surprisingly noisy. Typically they turn quite slowly, 20-60 rpm. Also they are described as being fish-friendly, though I can't say how much so in regards to which fish.

  • cool thanks will look into these. My father and I are not hydro anything - we are trying to find a vacation house to buy near a waterfall/river that we can use to power the house. Commented Oct 21, 2013 at 13:36
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    There's a community hydro project in Oxford near where I live using a screw; in order to get permission they had to install a fish ladder next to it so the design is evidently not completely fish-friendly.
    – aucuparia
    Commented Jan 29, 2020 at 13:50

As for the generator, scavenging a permanent magnet DC motor off an old treadmill is a good start. There a LOT of treadmills out there. When I got my camper I thought it would be nice to have some additional power from the wind to supplement my solar panel.

Put a listing on CraigsList asking for free treadmills for parts. The next day I had one with a good DC motor. Cost me nothing. I still have to complete that project, I would like to be able to put a water wheel on it, mount it on stakes in a creek or river in addition to putting it on a mast with wind blades instead if wind is more plentiful at a given site.

  • Not just treadmills. Pretty much any DC motor will generate DC electricity if you make it turn. Try this by hooking up a hobby DC motor to a multimeter, and then do what you can to turn the motor. Turn it with another motor if you like, but whatever. I first tried this experiment when I was about 10.
    – Ernie
    Commented Mar 17, 2016 at 21:23

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