I am a student designing a hydro electric generator used on rivers to collect kinetic energy from horizontal water flow, rather than potential energy from vertical water drops.

My idea is to turn a large wheel using the water flow, this is connected to a smaller wheel using a belt in order to increase RPM.

It is used solely to charge as many 17Ah 12V batteries as possible from the power generated.

A generator I have been looking at in particular is this: 1.3kw single-phase motor, 3400 RPM, 110VAC, 15.3A.

Here are my calculations:

  • Water velocity = 2m/s, big wheel circumference = 75cm
  • This gives 2.66 RPS which is 160RPM
  • to reach the 3400 RPM of the motor the small wheel must be (3400/160) = 21.25 times smaller
  • this means the circumference of the small wheel is (75cm /21.25) = 3.59cm
  • this in turn means the diameter is (3.59/pi) = 1.12cm

It seems like this is a very small wheel to be turning such a large motor. Is this diameter too small to function correctly?

closed as off-topic by LShaver, Jan Doggen, Fred, J. Chomel, A. A. Mar 23 '17 at 21:48

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  • Welcome to Sustainability.SE! I edited your question and title a bit to make it more clear. However, I'm concerned this may not be a good fit on this site, and may do better over on Electronics.SE. But, let's leave it for a bit and see if anyone here has some insight. – LShaver Mar 4 '17 at 16:01
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    My guess is that yes, that would be much too small. A belt would slip probably. This question may also be a good fit for engineering.stackexchange.com as they could likely suggest a solution... – Highly Irregular Mar 5 '17 at 1:07
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    How is this question different from one recently posted on SE Engineering? – Fred Mar 5 '17 at 2:07
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    I'm voting to close this question as off-topic because it's a better fit on engineering.SE, where it has already been discussed: engineering.stackexchange.com/q/14045 – LShaver Mar 6 '17 at 18:44