
Ask HN: Why not harness Gym energy? - econcon
Why not make machines through which workout is converted to electricity and enters the grid?<p>It seems it will help balance the renewable energy on grid.
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the_hoser
Humans don't produce a lot of usable energy that way. Let's say you burn 300
Cal riding that stationary bike for 30 minutes. That's barely 0.3 kWh. Most of
that energy you burned is just heat. The rest is minuscule. After subtracting
inefficiencies of the alternator, and transformers, and all the rest of the
hardware required to convert human power into electrical power... you're not
left with much. It would take far, far longer than the lifespan of the
exercise equipment to pay for the operation.

And, most modern cardio equipment _consumes_ more energy as electricity than
the user of the equipment is producing.

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jetti
There is a gym chain in the Chicago named Eco Gym[0] that uses solar and human
power to power their gyms.

[0] [https://www.ecogymworldwide.com/](https://www.ecogymworldwide.com/)

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bvandewalle
At that point it is more a PR play than really reusing the energy.

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hncensorsnonpc
Having not read anything about it. Why is it just PR? What energy does a gym
need? Solar and Homan power should be more then enough to power a few LED
lights and a fridge or something.

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bvandewalle
Because we are talking about a negligible amount of energy.

It would take more energy to build, install and maintain the equipment that
would be able to do that.

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smarri
I've always wondered why we can't do more with the kinetic energy of the
ocean. I know there are many projects and tidal energy companies. But
considering the scale of the ocean, waves, and so on, I've always been
interested to know why we haven't cracked it at a large scale.

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Someone
The huge amount of energy in ocean waves and currents, compared to air (water
is about 800 times as heavy as air) also is a challenge. It destroys anything
that isn’t built extremely sturdy.

And that’s just water. Sea water is salty. It destroys steel and electronics
even if it isn’t hitting it.

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smarri
Ah yes makes sense, it seems solar, then wind, would be easier to harness. I
just look at the ocean and see all that potential in the waves...!

