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Home made energy

  1. Jun 17, 2009 #1
    hi guys, would it be viable to rig up an exercise bike to run say your tv?
  2. jcsd
  3. Jun 17, 2009 #2


    Staff: Mentor

    Hi budd, welcome to PF

    That depends entirely on what you mean by "viable". Is it technologically possible, yes. Can a human generate that much power, also yes but not easy and may take some training to get in shape. Does it make economic sense, certainly not, food energy is much more expensive than electrical energy. Is it environmentally friendly, probably neutral, the extra CO2 you emit is probably more than the CO2 emitted from the power plant but it didn't come from fossil fuels.
  4. Jun 17, 2009 #3
    thanks for the reply. i was thinking along the lines of people keeping fit and using the energy instead of wasting it. maybe a niche market for such devices. would the technology be cost viable?
  5. Jun 17, 2009 #4
    On the plus side you'd become fitter.

    Edit: SNAP!
  6. Jun 17, 2009 #5
    Of course. Everything is possible in this world.
  7. Jun 17, 2009 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I hope that was a sarcastic remark ...
  8. Jun 17, 2009 #7
    Half way. But, setting a pedale bike to run your TV is not that much of an impossible mission.
  9. Jun 17, 2009 #8
    A television set uses a certain amount of power. I saw a flat panel rated around 200W. A human on a bicycle can generate 75W.

    These are watts or power units: energy per unit time.

    So it seems possible to find a TV in the desired range. Some of the generators I've seen are in the range of $500 US. Even if electrical costs were $.20 US for a kilowatt hour we'd have:

    200W = 0.2 kW
    1 hour of television uses (0.2 kW)(1 hr) = 0.2kW hr

    this costs (0.2kW hr)($.20/kW hr) = $0.04
  10. Jun 17, 2009 #9


    User Avatar
    Gold Member

    It's been done.
    Badda bump.
    Last edited by a moderator: Apr 24, 2017
  11. Jun 17, 2009 #10
    the home exercise market is massive and only getting bigger. why has this not taken off? i can only think it must be the cost. what are we looking at here. people would be buying the bike anyway. just the added costs of converting the energy. if its double the cost of the bike surely it's still viable?
  12. Jun 17, 2009 #11
  13. Jun 17, 2009 #12
    Get a small portable tv that runs on 12 v dc (under 50 watts). Use (buy or build) a pulse-width-modulated (efficient) dc-dc converter for the generator (dc pm motor running as a generator). The generator voltage is linearly proportional to RPM, so you need a good dc-dc converter.
  14. Jun 17, 2009 #13
    1 vs. 1 trading of human energy for industrial energy was not practival even in the second half of the 18. century, when Watt invented the first usefull steam engine. And of course is even less practical now. However it may seem reasonable to buy that bike if you like a lot of (indoor) physical exercise and you enjoy in a childish thought that you are doing something for the environment.
    I have a better idea: why don't we drive to work with a bike instead of a car (sadly, most people are too lazy)? This action has a much better ratio of trading of human energy for the industrial energy.
  15. Jun 17, 2009 #14
    i'm one of the none lazy people who does bike to work:smile:.... people are to lazy and with the uk adult population at 30% obese nowadays i was more thinking of the health issues than the environment. imagine if kids today had to bike for 30 mins to watch tv or play xbox. obesity would be 10% within 5 years:smile:
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