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Saving Electricity
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| As seen in Newsweek, the Christian Science Monitor, CNET, PC Magazine, InfoWorld, and everywhere else. |
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Saving Electricity |
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Yes, you can make energy with a bicycle. But it's unlikely to save you any money, because it generates such a small amount of electricity versus the cost of the setup. And it might not even be green energy, once you consider the energy that's used to produce your fuel (food). A typical bike generator can produce 100 watts. If you pedal for an hour a day, 30 days a month, that's (30 x 100=) 3000 watt-hours, or 3 kWh. Since the average cost of U.S. electricity is 12¢/kWh, that one month of pedaling saves you $0.36. Congratulations. If the system cost $400, it would take only 93 years to pay for itself. And that's before we consider the cost of food. If you're overweight, like most Americans, then you can consider your biking energy "free" since you could be burning fat. Likewise, if you ride the exercycle instead of doing some other kind of exercise that you were going to do anyway, then the cost of your energy is also free. But if you're not overweight and not exercycling instead of some other exercise, then you'll be buying more food to fuel your effort. Since it takes about 1 calorie to produce 1 watt-hour of electricity, your month of pedaling would require 3000 calories. With the cheapest food you can buy, oil or flour, you're looking at $0.85 to create $0.36 of electricity. Some savings. Prepared foods are even worse: Figure $5.41 for Cheerios, $6.15 for bananas, or $22.22 for Big Macs. But money aside, isn't bicycle power a form of green energy? The answer is that it depends on where you get your calories. Just as with the money costs, if you're overweight or exercycling instead of other exercise, then yes, the (piddling amount of) energy you create is indeed green. But if you're already at a decent weight and not substituting for some other kind of exercise, then you're going to eat more food to power your effort, and the pollution caused to produce that food is more than the pollution saved by creating your own electric. 3000 extra calories from what a typical American eats will make 30 lbs. of CO2e, or 15 lbs. for a vegan. By comparison, the energy from the power plant makes only about 5 lbs. of CO2e to generate the same amount of electricity. (sources) But what about putting the generators in gyms where people or exercising or using ellipticals anywway? Okay, let's take a look at the numbers: Texas State University put generators on 30 elliptical machines at a cost of $20,000. (source) If we generously assume that each machine is used 1/3 of the time over a 12-hour period, that's 30 machines x 1/3 utilized x 12 hours x 100 wH/hr x 1 kWh/1000 wH x 360 days/year = 4320 kWh/year, which is not enough to power even one typical American house for the same period of time. And cost-wise, the energy saved at 12¢ per kWh is worth $518 per year, so the payback time is close to 40 years, not counting maintenance or opportunity cost. Yeah, it's green energy, because otherwise the exercisers' energy is wasted, but the far easier solution is to just stop using ridiculous amounts of energy in the first place. A typical family can easily save more energy than that whole fleet of ellipticals at TSU can produce. This website gives concrete examples of how to do so. (Google picks the ads, not me.) Related sites
Last update: May 2009
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 All advice is given in good faith. We're not responsible for any errors or omissions. Electricity can kill you; if you're not competent to work on your electrical wiring then hire a professional to do it. |
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