How much energy does a treadmill and/or stationary bike create?

Question

If you could hook them up to out put the energy they create from a person exercizing on them, do you think they could power a gym?

Answer 1

According to the reference below Lance Armstrong can put out 500 watts for 30 minutes. This represents an extreme upper end. The typical gym cyclist could probably sustain about 100 watts indefinitely (according to the second article that's the power required for a 70kg person to walk at 3mph or bike at 16 mph).

While your idea is totally possible in principle, it is not economical (at least in the US). Let's look at the numbers:

Assuming you could convert 100 watts for 8 hours/day at 70% efficiency you could generate 560 watt-hours per piece of equipment per day. At 20 cents/kw-hr that's 11 cents/day or $40 per year. The cost of the gizmo to do that is probably many times $40 so would have a long economic pay back period.

All the energy of spinning and treadmilling is ending up as waste heat now that just heats the inside of the gym. Installing energy recovery gizmos would cut down on that heat load. So even if we double the $40 savings to $80 it still can't be economically justified.

However, in some places in the developing world it might be economically feasible, but those places typically don't have many gyms. People there don't have the luxury to have lots of surplus calories to burn off going nowhere.

Answer 2

well when i am doing the hand bike, with out using my feet, it says i produce about 70 watts.  so its enuff to power a 70 watt light bulb.

Answer 3

Its more of a matter of how hard the exerciser can work.

Lets say a guy can power a 75 watt lightbulb. 10 working that hard can power 10 light bulbs. No where close to what a gym would need.

Most gyms are also air conditioned, which uses in excess of 1,000 watts for some and 20,000 for others. Its better to have self powered machines to cut the ammount of juice used by the gym. The gym i go to has self powered treadmills, ellipticals and Bikes. That saves an unknown ammount of juice. Yet they are a/c'ed and have tvs going... its just impractical to try and power a gym with just the users.