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solar bud
Site Admin

Joined: 21 Oct 2007 Posts: 45 Location: Lancashire |
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| Thu Jun 19, 2008 8:11 am |
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adam2
Joined: 19 Jun 2008 Posts: 17 Location: London UK |
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Human powered generators can certainly be useful for small scale, short term or emergency power needs.
Most people though, until they have tried it, have a very inflated idea of how much power can be produced.
I recently asked a number of people* "what is the value, per hour, at normal retail prices, of the electricity that a person could generate by pedalling"
The answers ranged from 50 pence up to several pounds.
The answer is one penny! possibly two pence if you are very fit!
I recently produced 150 watts on a cycle generator VERY briefly, I could not sustain more than 50 watts. Someone fitter than me would produce more, but I doubt that many could sustain much more than 100 watts for any time.
*All members of a very green group
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| Thu Jun 19, 2008 11:06 am |
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Blue Peter
Joined: 19 Jun 2008 Posts: 6
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| adam2 wrote: | I recently produced 150 watts on a cycle generator VERY briefly, I could not sustain more than 50 watts. Someone fitter than me would produce more, but I doubt that many could sustain much more than 100 watts for any time.
*All members of a very green group |
Is the wattage measured differently than on a normal exercise bike? Judging by the ones at our gym, it shouldn't be too difficult to generate 150 watts for an extended period of time,
Peter.
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| Thu Jun 19, 2008 2:18 pm |
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adam2
Joined: 19 Jun 2008 Posts: 17 Location: London UK |
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I suspect that it may be measured differently, although I am not familiar with excerise bikes they probably measure watts of mechanical effort, not watts of electric power.
If the generator was 100% efficient then these two figures would be the same.
Since in practice the generator is not 100% efficient, the watts of electricity will be less than the mechanical input, perhaps by as much as 50%
It is also possible that the watts display on an excerise bike is optimistic in order to flatter the paying customer.
Alternativly you may be much fitter than the average, I would consider 150 watts achievable by an athlete, but not by mr avaerage (other than very briefly)
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| Thu Jun 19, 2008 2:39 pm |
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Blue Peter
Joined: 19 Jun 2008 Posts: 6
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| adam2 wrote: | I suspect that it may be measured differently, although I am not familiar with excerise bikes they probably measure watts of mechanical effort, not watts of electric power.
If the generator was 100% efficient then these two figures would be the same.
Since in practice the generator is not 100% efficient, the watts of electricity will be less than the mechanical input, perhaps by as much as 50%
It is also possible that the watts display on an excerise bike is optimistic in order to flatter the paying customer.
Alternativly you may be much fitter than the average, I would consider 150 watts achievable by an athlete, but not by mr avaerage (other than very briefly) |
50% efficiency would make sense. I reckon, when on top form, I could do about 300W for 15 minutes, which would translate nicely to your 150W electrical,
Peter.
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| Thu Jun 19, 2008 2:44 pm |
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Eternal Sunshine
Joined: 22 Jun 2008 Posts: 15 Location: Preston, Lancashire |
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Just think if all the exercise bikes in the land were linked up to generators somehow tho - that may produce a decent amount of energy. 
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| Sun Jun 22, 2008 6:10 pm |
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