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posted by hubie on Sunday December 10, @09:32AM   Printer-friendly

Low-tech Magazine has built a bicycle generator for a public exhibition on energy at the Pavillon d'Arsenal in Paris, France. Their two other bike generators can be seen and experimented with in Rotterdam, Netherlands and Barcelona, Spain.

In October, we built a third energy bicycle during a workshop at the House of the Future in Rotterdam. This bicycle generator is now used as an energy source in the community center. The House of the Future is open to the public, for details see their website and instagram.

In a future article, we will cover the construction process and technical details of these two new muscular power plants. These machines are based on spinning bikes and are more powerful than the first bike generator we built.

With electricity prices continually hitting new record highs, maybe the market is the EU?

[The Toaster Challenge can help put this energy-generation idea into perspective. --hubie]


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  • (Score: 3, Insightful) by looorg on Sunday December 10, @01:29PM (11 children)

    by looorg (578) on Sunday December 10, @01:29PM (#1336017)

    It could have been interesting, and educational, if they had some little chart that showed how long you would have to pedal for to charge common items -- like how long do you have to be on the bike to charge your phone or have the lights on etc.

    The best I can find in the article was a few layers down about building a bike powered air compressor but that is still somewhat lacking in how long it actually takes to fill the air tank.

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  • (Score: 5, Informative) by pTamok on Sunday December 10, @02:27PM (4 children)

    by pTamok (3042) on Sunday December 10, @02:27PM (#1336019)

    https://en.wikipedia.org/wiki/Bicycle_performance#Energy_output [wikipedia.org]

    How much power humans can generate and for how long varies with physical form. The specific power may be expressed in watts per kilogram of body mass. Active humans can produce 1.5 W/kg (untrained), 3.0 W/kg (fit), and 6.6 W/kg (top-class male athletes). 5 W/kg is about the level reachable by the highest tier of male amateurs for longer periods.[8] Maximum sustained power levels during one hour range from about 200 W (NASA experimental group of "healthy men") to 500 W (men's world hour record).[9]

    On that basis, you can probably use 200 Watts per hour as an approximation.

    IPhone batteries vary from about 4.25 Watt hour to 17.1 Watt Hour capacities. ( https://www.macworld.com/article/678413/iphone-battery-capacities-compared-all-iphones-battery-life-in-mah-and-wh.html [macworld.com] ), so assuming no losses (which is implausible), it's take between 5 and 10 minutes to generate enough power to charge an iPhone fully.

    A laptop PC has a battery capacity of 'about' 50 Watt-hours. That's 15 minutes of cycling, again, assuming no losses.

    This calculator

    https://www.omnicalculator.com/physics/water-heating [omnicalculator.com]

    tells me that at 100% efficiently, 200Watts will boil a quarter of a litre of water (enough for a cup of tea) in 7 minutes,

    A 'typical' PC and monitor will probably add up to 200 Watts power draw on their own. You would need to pedal continuously while working. As for gaming, you'd need several people pedalling to allow you to run a semi-decent graphics card and powerful PC.

    • (Score: 3, Informative) by captain normal on Sunday December 10, @09:49PM (3 children)

      by captain normal (2205) on Sunday December 10, @09:49PM (#1336056)

      A 24" LED monitor uses less than 30 watts. You'd have be driving a pretty big monitor to suck up 200 watts. The typical laptop uses far less than 30 watts.

      --
      Everyone is entitled to his own opinion, but not to his own facts"- --Daniel Patrick Moynihan--
      • (Score: 0) by Anonymous Coward on Sunday December 10, @10:06PM (1 child)

        by Anonymous Coward on Sunday December 10, @10:06PM (#1336057)

        And one litre is a damn big cup of tea.

      • (Score: 1) by pTamok on Monday December 11, @07:38AM

        by pTamok (3042) on Monday December 11, @07:38AM (#1336094)

        A 'typical' laptop PC, yes: but a 'typical desktop PC has a higher power draw. I didn't make myself clear.

  • (Score: 5, Informative) by JoeMerchant on Sunday December 10, @04:32PM (5 children)

    by JoeMerchant (3937) on Sunday December 10, @04:32PM (#1336025)

    It's not just how long but also how hard you pedal.

    My Physics 101 prof brought in a couple of generator bikes to demonstrate in 1985. They had variable loads 0, 25, 50 and 100 watts IIRC. Switch on a light and add load, 3 lights, max output with all on: 175W.

    I biked to class and all over town at the time, I biked 50 miles a day for weeks and a time a couple of summers later without any special preparation or training, in other words I was 18 years old and in reasonable shape.

    25W output was sustainable, but tiring for me, I probably couldn't maintain that output for more than an hour. 50W was hard, and I could only maintain the 175W output for maybe a minute.

    I may be mis-remembering the load levels, or maybe there was a significant inefficiency in the generator system, it seems like even today I could output roughly what my 250W rated eBike motor outputs for a minute or two, but regardless, 1000W is out of the question for a reasonable human powered generator to sustain for any length of time. Better to put 2 or 3 standard solar panels on the roof.

    --
    🌻🌻 [google.com]
    • (Score: 1, Informative) by Anonymous Coward on Sunday December 10, @05:08PM (3 children)

      by Anonymous Coward on Sunday December 10, @05:08PM (#1336031)

      That Toaster Challenge link shows what you're talking about where a Olympic-class cyclist was powering a 700W toaster.

      • (Score: 4, Touché) by JoeMerchant on Monday December 11, @12:47AM

        by JoeMerchant (3937) on Monday December 11, @12:47AM (#1336064)

        Seems like the toaster challenge setup had the same problem I complained about with the generator bike in physics class, gearing was too low - making you pedal too slowly for optimal power output. It's still hard, but when it bogs down like that it's even a bit harder. Robert might have made it to medium brown on the toast with more rider friendly gearing.

        --
        🌻🌻 [google.com]
      • (Score: 3, Funny) by ElizabethGreene on Monday December 11, @01:23AM (1 child)

        by ElizabethGreene (6748) Subscriber Badge on Monday December 11, @01:23AM (#1336065) Journal

        Special thanks to whoever posted that, BTW. That is an impeccably beautiful man.

        • (Score: 0) by Anonymous Coward on Monday December 11, @02:43AM

          by Anonymous Coward on Monday December 11, @02:43AM (#1336069)

          Here's one of the best sprinters and kilo riders to come out of USA, https://www.renehersecycles.com/people-who-inspire-us-nelson-vails/ [renehersecycles.com]
          They all have enormous legs. When I saw Vails at a velodrome I was still a skinny kid...and his legs had about the same circumference as my waist.

    • (Score: 3, Informative) by pTamok on Sunday December 10, @05:43PM

      by pTamok (3042) on Sunday December 10, @05:43PM (#1336034)

      I've always understood (perhaps incorrectly) that peak output power for a human is about one horsepower, which is 735.5 Watts, You can't sustain that for long.

      Wikipedia gives the following (cited) tidbit: "Over an 8-hour work shift, an average, healthy, well-fed and motivated manual laborer may sustain an output of around 75 watts of power." ( https://en.wikipedia.org/wiki/Human_power#Available_power [wikipedia.org] ) , and if you figure that as the input to an electrical generator or mechanical device, which will be less than 100% efficient, the actual usable power will be less.

      The BBC had a program where they powered a pretty standard house by using teams of volunteers on bicycle generators, adding more people as the demand went up ('Bang Goes The Theory: Human Power Station' [road.cc]). They didn't manage to meet the demand.