You could probably get electrical energy that is needed to run a gym (lights, accountant pc, vending machine) if you just install generators in all of this gym's exercise equipment

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Something like this has been prototyped by a group including the peeps behind low tech magazine: https://www.humanpowerplant.be/
It's really cool!

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Have you watched Nathan For You?

Nathan for You - Wikipedia

(en.wikipedia.org)

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6 guys simultaneously doing 100w for an hour has a much larger "relay pool" of available athleticism.

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That's fair. But that's still a lot of work for so little work, if that makes sense. Which is kind of what the demonstration showed.

A man at the peak of human athletic capability could barely put in enough energy on his own to slightly toast a piece of bread. Of course 6 people could put in one sixth of the effort, but that's six people still working such a small output.

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For a 2 slice toaster, they could make 60 toast per hour. Primitive human hunters had an endurance advantage over all prey, as sweat is a cooling system. They could run long enough to exhaust the prey. I still imagine horses could produce more electricity. Though apparently a horse can travel just 20-30 miles per day, while an average cyclist could do 60+.

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That's 1440 slices of toast per day. Using random numbers from google, that's 110k Calories worth of plain white bread. Assuming 6 people putting in the work, that's a bit over 18k per cyclist for 24 hours cycled, who each would require about 12k Calories for the work put in.

However, this is just to toast the bread, not to make the bread. I'm being a little dumb and taking this hypothetical a bit too far.

HubertManne

yeah. it still amazes me how much it takes to actually burn calories and its mostly heart rate that does it. I was thinking how you won't get anything from the free weights or aerobics classes along with swimming and heating pools, sauna, hot tub is not insignificant. I think it could be done as long as what the gym offers is limited and it uses very energy efficient things.

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Eh if you want to go real efficient you just drop the heating music and light and have only non electric machines and voilà! 0W used

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At the door there’s a bike. Start peddling to turn the lights on.

After a quick warmup, you can find your way to the rest of the gym. All the other machines also power the lights, air conditioning, showers etc.

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What if you have anxiety?

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There is a YouTube video around of a sprint cyclist powering a toaster and he can barely do it. I don't think you could do it "reasonabley".

DankOfAmerica

I do! How did you know?? I'm stressing out

socsa

A brand new rider makes around 50w off the couch. 100-200w functional threshold power is normal for someone who rides casually but regularly. Pro racers are doing like 5 w/kg so around 300w for a smallish person.

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Damn Marty!

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600w electrical output requiring 700w cycling power output is not sustainable human power output. TdF riders will usually output 1kwh over their full (4hr ride) day. Enough for 100 toasts

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It can still be worth adding generators and wiring to exercise machines to offset energy consumption

It seems like a lot of extra overhead for marginal benefit.

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If you get 15k hours and 1500kwh out of the machine, if electricity rates are 20c/kwh, that is $300 in savings. It's not amazing, but maybe "there's some appreciation value for members for the clean energy"

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Though apparently a horse can travel just 20-30 miles per day, while an average cyclist could do 60+.

A horse on a suitably adapted "bicycle" could easily travel 60+ miles; a cyclist without their bicycle would be closer to 20-30.

Captain Aggravated

i just want a stationary bike that can charge my phone.

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Most stationary bikes have a flywheel. You could 3D print a gearing set to run a small generator (like this one or DC) off if it. There are tutorials out there about how to set up it up.