## Main Question or Discussion Point

hi guys, would it be viable to rig up an exercise bike to run say your tv?

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Dale
Mentor
Hi budd, welcome to PF

That depends entirely on what you mean by "viable". Is it technologically possible, yes. Can a human generate that much power, also yes but not easy and may take some training to get in shape. Does it make economic sense, certainly not, food energy is much more expensive than electrical energy. Is it environmentally friendly, probably neutral, the extra CO2 you emit is probably more than the CO2 emitted from the power plant but it didn't come from fossil fuels.

Hi budd, welcome to PF

That depends entirely on what you mean by "viable". Is it technologically possible, yes. Can a human generate that much power, also yes but not easy and may take some training to get in shape. Does it make economic sense, certainly not, food energy is much more expensive than electrical energy. Is it environmentally friendly, probably neutral, the extra CO2 you emit is probably more than the CO2 emitted from the power plant but it didn't come from fossil fuels.
thanks for the reply. i was thinking along the lines of people keeping fit and using the energy instead of wasting it. maybe a niche market for such devices. would the technology be cost viable?

On the plus side you'd become fitter.

Edit: SNAP!

Of course. Everything is possible in this world.

Hootenanny
Staff Emeritus
Gold Member
Of course. Everything is possible in this world.
I hope that was a sarcastic remark ...

Half way. But, setting a pedale bike to run your TV is not that much of an impossible mission.

A television set uses a certain amount of power. I saw a flat panel rated around 200W. A human on a bicycle can generate 75W.

These are watts or power units: energy per unit time.

So it seems possible to find a TV in the desired range. Some of the generators I've seen are in the range of $500 US. Even if electrical costs were$.20 US for a kilowatt hour we'd have:

200W = 0.2 kW
1 hour of television uses (0.2 kW)(1 hr) = 0.2kW hr

this costs (0.2kW hr)($.20/kW hr) =$0.04

OmCheeto
Gold Member
It's been done.
http://online.wsj.com/public/articl...2db3gi3uvYlQ53I8a_ak_20070308.html?mod=blogs"
Harvesting the Energy Of Hong Kong Gym Rats; Lighting Up Dance Floors

......

David Butcher, a 52-year-old manager at a Web company in Los Gatos, Calif., works out daily on a homemade exercise bike he has hitched up to a generator. So far, he has used the bike to power his TV and operate his Roomba robot vacuum cleaner. He once jump-started his car after 30 minutes of pedaling.

"I have an excess of physical energy," Mr. Butcher says. "I needed an outlet for it."

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the home exercise market is massive and only getting bigger. why has this not taken off? i can only think it must be the cost. what are we looking at here. people would be buying the bike anyway. just the added costs of converting the energy. if its double the cost of the bike surely it's still viable?

Get a small portable tv that runs on 12 v dc (under 50 watts). Use (buy or build) a pulse-width-modulated (efficient) dc-dc converter for the generator (dc pm motor running as a generator). The generator voltage is linearly proportional to RPM, so you need a good dc-dc converter.

1 vs. 1 trading of human energy for industrial energy was not practival even in the second half of the 18. century, when Watt invented the first usefull steam engine. And of course is even less practical now. However it may seem reasonable to buy that bike if you like a lot of (indoor) physical exercise and you enjoy in a childish thought that you are doing something for the environment.
I have a better idea: why don't we drive to work with a bike instead of a car (sadly, most people are too lazy)? This action has a much better ratio of trading of human energy for the industrial energy.

1 vs. 1 trading of human energy for industrial energy was not practival even in the second half of the 18. century, when Watt invented the first usefull steam engine. And of course is even less practical now. However it may seem reasonable to buy that bike if you like a lot of (indoor) physical exercise and you enjoy in a childish thought that you are doing something for the environment.
I have a better idea: why don't we drive to work with a bike instead of a car (sadly, most people are too lazy)? This action has a much better ratio of trading of human energy for the industrial energy.
i'm one of the none lazy people who does bike to work.... people are to lazy and with the uk adult population at 30% obese nowadays i was more thinking of the health issues than the environment. imagine if kids today had to bike for 30 mins to watch tv or play xbox. obesity would be 10% within 5 years