Pedal powered electricity generator

The Professor would be proud of David Butcher of San Jose, California. He built his first pedal generator prototype in 1976. Every morning, he spends 45 minutes on the stationary bicycle generator to charge up a bank of salvaged batteries. Having mastered the machine, Butcher now sells plans so you can build your own. The cost of the parts is around $230, he says, or much less if you recycle an old bike. If you're interested in learning more, Butcher hangs out in a videochat room when he's pedaling away every morning. Apparently, he cranks out 1.8 kilowatt-hours a month. Of course, er, YMMV. Butcher has videos demonstrating the generator directly powering a blender (video above), washing machine, and breadmaker. His bike blender was even featured on a recent episode of MAKE: TV. From Butcher's site:
Pedalgenennn-1 My pedal generator is in the garage, hooked up through the Trace C12 controller in my Micro Solar Energy System to a recycled battery pack from my Sparrow Electric Car. I work out in the early morning, and it's dark. It would be pointless to use as much energy to light the workout area as I generated with the workout, so I light the area with the 12 volt LED Bar Light I put together several years ago. It uses white LED's to light the workout area. They require almost no power, so virtually everything I generate ends up in the batteries.
The San Francisco Chronicle profiled Butcher last year. Butcher digs alternative power tech in general, having installed solar panels on his roof and X10 modules throughout his house for intelligent control of appliances and other devices. From the SF Chronicle:
Butcher, who lives alone after a divorce, traces his environmental leanings to the 1969 Santa Barbara oil spill, which marred miles of coastline with 200,000 gallons of crude oil. Butcher was 14 at the time and witnessed it firsthand. He built his first pedal generator when he was in his early 20s.

"I was always interested in alternative energy and solar in particular," he says. "I was living in Portland, Ore., where solar is not as much of an option. So I thought, 'What else could I do?'

"I'd been on a swim team for years and I was in pretty good shape, and I thought there must be a way to get some power going."

Butcher's prototype bicycle was chain-driven and featured a welded steel frame. Today's version, with its simplified drivetrain and bolted frame, can be assembled with basic hand tools.

When he took up his pedaling regimen two years ago, Butcher tipped the scales at 180 pounds. Today, at age 53, he weighs a lean 150 and possesses a pair of legs that wouldn't look out of place on the Olympic cycling squad. Butcher's pedaling has become so efficient that he has pretty much abandoned his car (electric, incidentally) in favor of bicycling, reducing his carbon footprint still further.
David Butcher: Pedal Powered Generator (via BB Gadgets)

"Stationary bike designed to create electricity" (San Francisco Chronicle)


  1. Portland, OR isn’t a place where ‘Solar is not really an option’. We’re above the median for sunlight in the US. We were just named an American Solar City

  2. So the question is, why are we wasting all this energy that could be generated by people in spin classes at the gym? How hard would it be to use this technology to make every gym in America generate it’s own power? (and possibly even feed some back into the grid, making those membership fees lower!)

  3. people can sustain about 0.1 horsepower. athletes can sustain maybe 0.3 horsepower.

    that’s about 75 watts of power… per hour… for us regular folk.

  4. @#1:

    A good proposal, but the answer is basically “because it would require more effort.” The amount an individual gym would stand to profit probably doesn’t make it worth the logistical and technical hassle of running a small-scale power plant.

    I could see a gym like that taking root in an especially liberal city like Berkeley that could use their “green” cred to attract more customers, but electricity is still so cheap right now that many businesses don’t even turn off their lights when they close for the night.

  5. I’m sure it’s worth it for a gym to have these power generating exercise bikes built. Think of the marketing…. your drive to lose that weight, and “power the school next door” will give people new inspiration to burning those calories!

  6. I love gadgets, and this is cool. BUT: Why use mechanical energy to generate electricity with low efficiency, store it with low efficiency, invert it with low efficiency, then turn it back to mechanical energy with low efficiency, when there is a simple alternative:

    use pedals to turn the blender directly.

    For example

    We have a (mechanical) bike blender at our local farmers’ market…

  7. The blender one is a bit perverse. Bicycle (or hand crank and flywheel) + gears, direct to blender would be less so. Knife, (fine chopping) followed by pestle and mortar less still.

    Having read the bit on his site where he in fact fails to power a washing machine through its entire cycle, I have to conclude that perversity is the object of the exercise, or exercise is the object of the perversity.

  8. $230,

    he cranks out 1.8 kilowatt-hours a month

    Thats about twenty-cents per month. $2.40 a year. It’ll take a hundred years just to pay for the equipment.

    1. Next you’ll be telling me that burning my liposuction fat is an inefficient way to heat my home.

  9. I wonder how many years he would have to pedal to erase the carbon footprint of the parts involved. sure, the battery’s recycled, but how about that inverter, the generator, the wood, the bicycle, the fancy blender…

  10. I bike for fun, and for transportation. The body is about 25% efficient, so for every 4 calories consumed, you can only output 1 calorie of energy.

    I realized that my efforts at being “green” were offset by biking for fun. I’m sure I’m producing a lot less CO2 than a gas burning car, but I still produce quite a bit as my muscles turn Oxygen into CO2.

    Also, the excess food I eat (about 10,000 Calories per day when I’m biking every day in the summer) requires fields to grow in and trucks to ship it. I can’t afford 10,000 Calories of locally grown, organic food, either.

    Turning energy that would normally be spent at the gym towards generating power is good, but exercising more to generate power isn’t. Nuclear and wind probably produce less CO2 than a human. And they can provide more than the 150Watts I can sustain for only 10hours/day.

    Bike instead of drive, but don’t bike to generate power. It’s inefficient and impractical.

  11. I’m sure I’m producing a lot less CO2 than a gas burning car, but I still produce quite a bit as my muscles turn Oxygen into CO2.

    Apples and oranges.
    The CO2 you exhale came from plants that sequestered it from the air. The CO2 your car produces was previously locked safely up deep underground. In other words, your bicycle is carbon neutral, but your car is not. (Minus the carbon used to get your food to you, of course.)

    Finally, all of humanity’s exhaled C02 adds up to 0.6 billion tonnes per year, 3.1 billion tonnes if you include livestock and waste decomposition.

    Fossil fuels add up to more than twice that:

  12. Oh, my God!

    This gave me a flashback from the very disturbing and nauseating, but hysterically funny, movie “Res aldrig pÃ¥ enkel biljett” by Carl Johan De Geer. It has a scene that, if I remember correct, is almost identical.

    Of course I don’t think this movie will ever be distributed outside Sweden as it contains some hyper-realistic (and very unsexy) sex scenes, as well as a lot of other stuff that will give you nightmares for months.

    Why do I feel a sudden urge to see this movie again? It took me years to suppress the memory of the first time i saw it. Damn Boing Boing!

  13. @#10: Ten thousand calories per day? I’m impressed – riders in the Tour de France are generally estimated to use slightly less than that, while riding more than 100 miles per day, at better than 25mph (my apologies to most of the world, make that 160K, at around 40Kph). I ride around 20 miles every day, and by my estimate, I need perhaps an extra 500 calories. Cycling is very efficient. Though with panniers full of groceries, I do use more energy…

  14. For exercise, great. But, let’s see, 1.8 kW-hr at $0.09/kW-hr…that comes to 16 cents. Per month.

  15. Anyone interested should also check out CCAT at Humboldt State University. (Just Google ‘ccat hsu’) About->Projects->Archive->Pedal Power They have tons of related material.

  16. Alright, so this guys bike isn’t going to save the world and it’s not going to save him much money. However, it is going to charge the batteries he wants to charge (that he’s salvaged) and he’s going to get some exercise done at the same time.

    Now, if this guy can do it once with $230 (including a bike) why can’t every manufacturer of exercise bikes, treadmills, virtually every form of exercise machine (which essentially just machines that are designed to waste human energy) have a cheapo generator attached somewhere and somewhere to plug in a few batteries, better yet. Why doesn’t every house come with both plugs that provide electricity and plugs that allow you to easily plug in anything that generates electricity back into the grid.

    Surely Gyms would be the first place to start implementing this and I really can’t see how it wouldn’t start being cost effective after a short amount of time (once a few manufacturers start implementing the tech it’s bound to become fairly standard).

  17. Actually this idea has been implemented here in the Philippines where the inmates are required to take turns in using a stationary bike to recharge a battery so that they could have their share with the power. The article is here:

    Wouldn’t it be a great idea if they purchased used stationary bikes instead to save money? And they should use the recumbent stationary bikes instead so that more energy optimized in recharging the battery than moving a lot of muscles in an upright stationary bike. If you guys don’t know the difference here is another article that states the different types of stationary bikes that you might be interested in.

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