Retrospectacle: A Neuroscience Blog

Walking around the gym, watching all those people spinning or walking or treading or ellipsing….wouldn’t it make good sense to harness all that rat-race energy as power? Could you imagine getting a free gym membership for spending a certain amount of time on power-generating machines? Well, seems plausible enough, and may actually be coming to A Gym Near You.

The California Fitness club in Hong Kong is among the first to jump on the green energy treadmill — stairmaster and cross-training machines at the gym have been wired up to the building’s lighting system. If other gyms follow suit, it could kick off a new motivational craze, in which sweat equals glow.

….the Hong Kong scheme is one of a new wave of ‘energy recapture’ ideas aimed at harnessing the surplus power of casual activities, to generate electrical power that would otherwise come from the national grid.

But wait, folks, it gets even better.

Other recapture ideas include using the energy of footfalls to light up pedestrian tunnels, and military backpacks that use the wearer’s movements to refrigerate the medical supplies inside. And a Dutch nightclub has even installed a dance floor that lights up when tiny ‘piezoelectric’ crystals inside it are deformed by the dancers’ feet.

But how much energy is being generated? Is it really enough to make an impact on “dirtier” sources?

When all 13 machines at the Hong Kong gym are being furiously pedalled, the energy output is only enough to power five 60-watt bulbs. And even if they were used for 10 hours a day, it would take the club 82 years to pay off its US$15,000 investment.

Uhhh, so I guess its more of a gimmick (or exercise-motivational technique) than a practical energy netting solution. And what about the uber-cool Dutch dance floor? An uber-cool $260,000–much more than they will save on their lighting bill.


  1. #1 J-Dog
    March 5, 2007

    Shelley – Why you got to be such a playa hater… I was counting on using this to pick up some in-shape eco-chicks…

    Plus, don’t forget this OTHER down-to-earth gym promo:

  2. #2 Jason Black
    March 5, 2007

    It’s not all about the money. I agree, that as practical, carbon-reducing strategies go, these examples leave a bit to be desired. Analyzing them in terms of money, though, misses the mark on two counts. First, what you really want to analyze them on is the ratio of power produced by the scheme to power consumed in enabling the scheme in the first place. E.G., how much energy did it take to produce that piezo-electric floor? How much energy will the floor save over its useful lifetime? If that ratio is less than one, you’re in the clear.

    For nearly all such “casual energy” schemes, that won’t be the case.

    However, I would argue that such things are still worth doing, for another reason entirely. Because, as I said, it’s not all about the money saved. There is a sense in which is it hugely valuable to expose ordinary people to the energy flows going on all around them, all the time. To make them aware of what’s going on with the energy, and to start changing their thinking around how those flows _should_ be going.

    Because if getting somebody jazzed up about using a power-reclaiming treadmill at the gym gets them to realize that it’s a lot of hard, sweaty work just to light up a 60 watt bulb, then when they get home they may think twice about flipping on the lights right away. They may wait until the sun actually goes down before turning on the lights, if they understand that “oh, hey, if I flip this switch on, I’m lighting up three 100 watt bulbs in my living room, and there’s nobody on any treadmills generating that power. That power comes from carbon.”

    It’s not the power saved or generated, or the money saved, or even the carbon saved that’s why funky deals like self-lighting dance floors are worth doing. It’s because they help educate people to the real cost of energy.

  3. #3 Shelley Batts
    March 5, 2007

    Hi Jason, thanks for commenting. I think you’re onto something, and after giving it a bit more thought I came to two conclusions as to why this kind of thing is valuable. 1) It gets people confortable with acquiring energy in different ways, and gets them thinking as to where the energy actually comes from (as you mentioned).
    2) While the technology may not be efficient now, that doesn’t mean it won’t become efficient. This requires the public’s interest as well as tax dollars for research.

  4. #4 PeterC
    March 5, 2007

    It’s 25 * 12 watt low energy bulbs. Which are equivalent to your 60 watt. I can’t wait for this to develop. We already have a society so divorced from nature that kids and adults don’t know any more about milk than it comes from bottles. Vegetarians who would eat a BLT sandwich because it’s meat free. Now it’ll be electricity comes from lots of men working out.

  5. #5 Cat Faber
    March 5, 2007

    Actually, I like this idea for use with the TV at home. Maybe only a little of the power the TV draws would actually come from your stationary bike–but having to pedal to watch TV would be a great way to either get in shape, or give up watching the boob tube and do something better with your time.

  6. #6 Cameron
    March 6, 2007

    A little cost/benefit comparison-

    Body fat contains 3500 calories per pound, moderate cycling burns ballpark 600 calories per hour. At 65% VO2Max, about half of those calories will ultimately come from fat. So one pound of fat will provide for 12 hours of biking. That biking produces about 5 cents worth of energy.

    Since one pound of fat can be converted into one pound of diesel (9 fat:1 methanol), and there are 6 Kwh of energy in a pound of diesel, that’s $0.90 @0.15/kwh for one pound of fat through lipo. It costs about 15kwh per day to run a very basic clean room with basic lighting and an aspirator. So we’ll call it a 2 hour surgery and round up to $1 electrical cost. A lipo aspirator on e-bay will close at less than $1,000

    A typical lipo would remove about 10 pounds of fat, worth $9. Minus the methanol @$1 in bulk, electrical @$1, you’d still be making $4/hr. That’s plenty to pay the rent on a room somewhere if you’re open 10 hours a day, and still have a little left over to work off the micro-loan on an aspirator. The doc can be paid by the patient who can spend the 10 hours they don’t have to spend on the bike working to afford it (all for 10 times the weight loss). And most importantly no 83 year payment plans.

    That’s all to say that if we want to make good use of our fat while losing weight bikes attached to servos is a bad answer.

    If the real purpose is to get people motivated about getting heart healthy while educating them about energy concerns, then get Green Peace to co-sponsor the bikes with some record labels. Every bike gets an mp3 player that’s powered by your pedalling. The mp3 player contains new CDs from the label, environmental news reports from green peace, and anything else they can think to put on. They both get good press. A bluetooth receiver hooked into a LAN could automate the news/CD update process at gyms all over the world.

    The point is that transforming chemical energy in our body->body motion->mechanical motion->energy in a power grid->energy in an appliance will NEVER be MORE efficient than going body energy->energy in a power grid->energy in an appliance. If you want to use your fat to help the planet, the best way is to avoid appliances. That means taking the bike to work, stirring things by hand, etc.

  7. #7 outeast
    March 6, 2007


    That was maytbe the funniest comment I’ve seen on a SciBlog:)

    Y’know, except for the boring valid suggestions and points at the end there.

  8. #8 anonymouse
    March 7, 2007

    The nightclub that uses piezoelectric crystals to light up the floor isn’t doing that to save money on electricity, they’re doing it because it’s awesome to have the floor respond the your footfalls. This is the easiest way to have the floor light up with the dancers’ movements.

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