Exercise R Us

Question:

        I have played with various bike powered generators and found 50watts to be typical, of the power you can routinely get for any extended time. After about 1/2 hour you really know you have been doing some serious work but find it’s only enough to run your color TV for 15 minutes. You also start to consider the $300+ price tag for a 50watt PV panel as a more reasonable investment of your efforts. I’m still hoping to get a Schwin Exercise bike that I can hook up for a demonstrator but the $600 price tag on a new model has me looking for a used one.         For lights you could probably produce enough power to run a couple of compact flourescents. On the computer, unless you have a LCD display, forget it. The monitor normaly puts them above the 100watt range. While a car alternator or generator could be used, part of your work is being diverted to maintain the magnetic field. Permanate magnet motors make a better choice. I have heard about the book from New Zealand about building your own alternator/generator but the $65 price tag and lack of access to a machine shop have discouraged me so far. — University of New Mexico in Albuquerque New Mexico, 2701 Campus Blvd NE 87131-6046 USA     Phone: 505-277-8235

Response:

Interesting that 50 watts is indeed not much for continued bike electric generation. I had read articles about champion cyclists clocked for those human powered land (and air) records at generating something like half a horsepower or so (about 350 Watts) but probably not for long!! As for setting up a home generating system for small appliances using pedal power…. the old radio shack computer I am using right now is hooked up to a black and white tv (12 inch) which is only 35 watts rated…so I could do it I suppose. though watch out for power surges…. I have always wanted to set up a scenario-punishment for the real tv-couch-potato-hopeless addict: they MUST pedal at a certain minimum rate or the tv in front of them will simply NOT turn on…. cheers David Smith —

Response:

>Interesting that 50 watts is indeed not much for continued >bike electric generation. I had read articles about champion >cyclists clocked for those human powered land (and air) >records at generating something like half a horsepower or >so (about 350 Watts) but probably not for long!! >As for setting up a home generating system for small >appliances using pedal power…. >the old radio shack computer I am using right now is

Anyone care to calculate the amount of power that could be generated by a certain fraction of the prison population in the U.S.  We already pay for food and medical care plus recreation; merely substitute the recreation.   Cruel and unusual, maybe, you’d have to ask a constitutional law specialist. db

Response:

It is estimated that Eddie (the cannibal) Merckz deliverd 450W average, in setting the hour cycling record 20 years ago. The record has since fallen many times, on better equipment, by cyclists delivering no more than 420-430W. Martin

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>It is estimated that Eddie (the cannibal) Merckz deliverd 450W >average, in setting the hour cycling record 20 years ago. The record >has since fallen many times, on better equipment, by cyclists >delivering no more than 420-430W.

That’s, of course, Watts mechanical, not Watts electrical. Taking into account mechanical losses, alternator losses (both in theory very small) and storage losses (more substantial), usable electrical output would be less. And few people indeed are super athletes such as Merchz. There’s also another consideration that people are overlooking. Where is the energy coming from that powers the human pedaler? It’s coming from increased food intake of course. Humans aren’t very efficient energy conversion machines, it takes about 850 Calories to generate 200 Whr mechanical. That’s about a one third increment in the average American’s daily food intake. Can you increase your food intake by a third for two cents, the grid cost of the power you’d generate with that extra food? And how much extra energy would be required to grow, harvest, process, ship, and deliver that food to your table? More than 200 Whr? I suspect so. Gary — Gary Coffman KE4ZV          |    You make it,     | gatech!wa4mei!ke4zv!gary Destructive Testing Systems |    we break it.     | uunet!rsiatl!ke4zv!gary 534 Shannon Way             |    Guaranteed!      | emory!kd4nc!ke4zv!gary Lawrenceville, GA 30244     |                     |

Response:

– Hide quoted text — Show quoted text ->It is estimated that Eddie (the cannibal) Merckz deliverd 450W >average, in setting the hour cycling record 20 years ago. The record >has since fallen many times, on better equipment, by cyclists >delivering no more than 420-430W. >That’s, of course, Watts mechanical, not Watts electrical. Taking into >account mechanical losses, alternator losses (both in theory very small) >and storage losses (more substantial), usable electrical output would be >less. And few people indeed are super athletes such as Merchz. >There’s also another consideration that people are overlooking. Where >is the energy coming from that powers the human pedaler? It’s coming >from increased food intake of course. Humans aren’t very efficient >energy conversion machines, it takes about 850 Calories to generate >200 Whr mechanical. That’s about a one third increment in the average >American’s daily food intake. Can you increase your food intake by >a third for two cents, the grid cost of the power you’d generate with >that extra food? And how much extra energy would be required to grow, >harvest, process, ship, and deliver that food to your table? More than >200 Whr? I suspect so.

Well, at least the waste products are easy enough to handle. Heck, we already have the infrastructure in place! Bring on those prisoners! I wonder if Schwinn would offer volume discounts on Aerodynes. …Scott Barton

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