You just have to use a form of fusion.
That’s what they did in The Matrix.
While it may indeed cost $20,000 to retrofit an existing machine with a generator to capture the energy, it seems like it should cost much less than that to build a brand new machine designed for energy capture. If a building already uses solar panels to reduce its power usage, then it already has most of the power infrastructure needed to turn the variable exercise machine power into usable building and/or grid power.
So if it costs “only” $5000 to add a generator to a machine and connect it to the building’s power supply, and if the machine can capture 10,000 KWh annually at California’s average $0.15/Kwh rate for electricity, then the payback period could be as low as 3 years.
Whoops, now I see that the article was referring to the cost to retrofit 28 machines, rather than one machine. $714 per machine seems much more resonable, and even a bit low if the cost to integrate into the building’s power supply is included.
The 10,000KWh/year should have tipped me off, since there’s no way a single machine could generate that much power.
I worked at St. Potato’s College from 1977-1999, until it got too weird for me. Since then, they seem to have become even more eccentric. Quoting from their Climate Action Plan (PDF) [cover date 2010, actual PDF date 2012]:
“A green gym is under consideration which would require significantly less grid electricity than the current fitness center. Students would generate energy by either running or pedaling energy-producing cardio equipment. The energy generated would be used to power the majority of the remaining lighting and plug loads within the fitness center.”
They claim that this change alone will reduce carbon emissions from the gym by 60%.
About the only good thing I can say about it is that it will probably be more effective than the “Empty rooms love darkness” stickers on all the light switches, since if nobody is pedaling, there won’t be any power for the lights.
A few batteries would suffice to handle that objection, but, yes, if no one is there, a motion sensor would shut off the lights, and turn them on when someone came in.
Studies readily accessed on Google show that 75 watts is typical, with well conditioned athletes capable of close to 450 watts for short periods.
75 watts provides, with the new energy efficient bulbs, the equivalent of about 350 watts of illumination. That is quite a lot, enough for a decent portion of an exercise area.
Heat? Cooling? Computers? I think you’d need a fair number of people 24/7 to keep a facility in full supply. If you had enough business to generate a KW per hour, 12 hours a day, at the end of a month you might be saving $40. I don’t think the cost of outfitting a facility could possibly be offset with that small a return.
Although one might count as a benefit the not powering the machines … how much energy does a fitness center treadmill use in an hour?
What about a small DC generator, not wired into the building, but just powering a couple of USB ports on the machine, for the user to plug their cellphone or IPad or tablet into while they’re working out? You wouldn’t even need a battery, just a decent sized capacitor.
The marketing makes it worth the (probably much lower) cost. “I power my IPad myself!”
There is the minor consideration that self-powered treadmills do not feel the same as motorized treadmills. Your body position has to shift to push the tread belt, and there’s this complex thing where you are more likely to move yourself than the belt, so you have to hold on to the handles to react that push. It is difficult to get the speed, and it just feels different than regular running.
That is why powered treadmills were invented in the first place. The unpowered ones did not work well.