[clug] Exercise and pay the bills!

Alex Satrapa grail at goldweb.com.au
Tue Feb 10 00:31:01 GMT 2009

```Some food for thought:

One guy's story, no recipe: http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/08/23/HOKO11469A.DTL&hw=david+butcher&sn=001&sc=1000

Includes a recipe: http://www.humboldt.edu/~ccat/pedalpower/hec/hpeg/index.html

Cylec commercially available bike (Korean or Kenglish): http://www.cylec.com/

A narrative: http://www.pic101.com/solar/bikegen.htm

I love that first link - pointing out that the simple process of
boiling the water for a cup of coffee was more work than the author
could manage.

For reference purposes, a (white) MacBook draws 2.5W in standby (ie:
lid closed, just charging the battery with a small maintenance charge
for memory) and about 24W when it's running. I would assume an error
of half the last significant digit on that meter (though my colleagues
assure me it's bound to be within 10%).

How much power could you expect a human to generate? Depending on who

I'd always been told a rule of thumb that humans could produce about
1/8th a horsepower. 1HP is about 750W, so that's pretty close.

As for alternatives to riding a bike, check out http://wiki.laptop.org/go/Cow_Power
- they're working on a design where you tether a cow to a long lever
and walk the cow around in a circle pushing the lever, which is run
through a few up-ratios to spin an alternator. I would suggest an old
10-speed bike for the first stage, perhaps running the alternator off
a belt looped around the rim of the 700c wheel. I expect a similar
mechanism could work with a rope and belt or shoulder harness for
humans.

As for dynamos versus alternators - the advantage of an alternator is
that you can adjust the strength of the magnetic field in the rotor. A
dynamo has fixed magnets, which means it's really only good for
generating a specific voltage at fixed RPM.

The next step after a static exercise bike, of course, is figuring out
how to attach a high efficiency alternator to your pushbike, storing
the generated electricity in an accumulator of some kind (deep cycle
you ride to work.

Ultimately, what you need to do is stop using electric lights, TVs and
stereos. Just accept that it gets dark at night time, and learn to
enjoy reading books or playing card games with your friends. The power
you don't use is more valuable than the power you generate "for free"

Enjoy :)

PS: There is an "airline" adaptor available for the MacBook, which has
a connector on it that *looks* like a cigarette lighter fitting. Don't
be fooled :)  Airplanes supply 16.6V to the connectors, while cars
produce a maximum of about 14V. I think the MacBook can handle up to
20V, so I'm not sure that connecting it directly to a 24V supply would
be a good idea - though avoiding the DC -> inverter -> AC -> power
pack -> DC conversion sounds appealing.

```