Power Your TV, Cell Phone, or Laptop by Pedaling
by Jasmin Malik Chua, Jersey City, USA 
on 08.27.07
One of the first-prize winners of our TreeHugger/Popular Science/Instructables Go Green contest, this gadgetry wizard shows you how to rig up your bicycle to create a human-powered generator. His instructions are fairly detailed and incredibly involved—we won't pretend to understand all the mechanics involved—but now we want to make one for everyone we know for Christmas, Hanukkah, and Kwanzaa.
Here's the cost breakdown of the entire setup, illustrated below the fold:
Alternator = $89 (new); $15 (used at junkyard)
Bike Stand = $90 (new); $15 (on Craigslist)
AC Inverter= $60
2 Farad Cap = $50
Wiring and enclosure Hardware= $100
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Why not modify the alternator to put out AC electrity at 110v so that you don't waste the heat on the inverter?
This is cool. Could you hook up 2 or more together to generate more watts? (or would that just increase the voltage, my knowledge of electricty is very limited).
Great stuff - we have one of those bike trainers laying around the place that hardly gets used, plus all the 12v/inverter gear. I'm totally inspired by this!
Recumbent? Conventional bikes hurt my butt and mah knees.
I remember a scene from the movie "Soylent Green", where Sol was pedaling with such a device to power up the batteries they used in their apartment.
Unfortunately, the pic above is misleading. The car alternator may very well have a maximum capacity of 296 watts, but a human being pedaling on a stationary bicycle can only generate an average of 50 watts, a maximum of about 100 watts at full speed.
That's enough to continuously power a single light bulb.
This guy is obviously running his TV and Playstation 2 off of stored battery power. He'd be better off with solar cells and or a small windmill.
He's only powering the PS2, not the TV. PS2s can actually be converted to run on 12v, mostly used in car installations. This would bypass the need for the inverter. Many LCD screens are also able to run on 12v, and with their low power usage, one would be able to run both from pedal power.
A better solution is to hook the alternator to a small bank of deep cycle batteries, so the system doesn't power down as soon as you stop pedaling. With batteries in place, you can charge them for later use, or switch out riders multiple times without interrupting the system.
Another benefit of using a battery bank, is that small effort (50w) can be exerted for a longer time, allowing a heavier load (200w, which is too much output for anyone to sustain) and be used in a shorter amount of time. Pedaling for 10 minutes at 50w would allow you to run an 800w microwave for 30 seconds (ignoring conversion losses), something that you could never do being connected directly to the load.
A brushless generator would also be a better choice, but maybe not the cheapest.
Check your numbers, A Non. The average person is capable of about 100W continuous, recreational cyclists are usually between 200 and 300, and professional racers can approach 400. In a sprint, a pro can approach 1000.