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Exercise bike that can store 2KWh of electricity
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this post was submitted on 12 May 2024
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TLDR: It's a great concept but it's about 100× more exhausting than you imagine.
I absolutely love stuff like this, and I also love cycling.
However, there is a big caveat here: I've been cycling for years and know my own power output:
Output -- Time Window -- Heart Rate
*(yes, I know. My thighs are larger than some people's torsos and it scares me too)
That means that on average, around 13 and ½ hours of pedalling to charge this thing. (2 KWh is also worth $0.68¢ where I live at standard residential rates).
Humans are not great at converting their physical and thermal energy into kinetic or electrical (20-24% for most bodies).
Pedal power is amazing for things like charging phones or powering small devices and computers though, or for something completely meta: Charging up a eBike or electric scooter (120W), to then use without pedalling later.
Which then begs the question -- if our "human/person power output" is like 150 watts constant .. and the sun provides 1.4 kW/m² of energy -- why not just lay down a 150W photovoltaic solar panel ($89) in the sun and sip on some unsweetened iced tea instead?
While what we can generate is negligible. If, for example you had these in all gyms, that's generating something. Not a lot, but more than nothing. Also all houses should have batteries and being able to remove the cost of a phone charge from what you suck from the grid would be nice.
It's still unlikely to pencil out to do this given the opportunity cost of actually going through the effort of building, buying and connecting these things, to be honest.
I'm fascinated by the idea but it's important to remain realistic.
Here's a good article on the concept of bicycle generators: https://solar.lowtechmagazine.com/2022/03/how-to-build-a-practical-household-bike-generator/
Personally, I think the best application of this concept is probably direct use of the mechanical energy, without converting the energy to electricity at all. See the bicimaquinas-concept: http://www.mayapedal.org/index.en
One of the wonderful things about bicycles is how extraordinarily efficient they are - very little energy is required in relation to how much transportation work you get out of it. This works against us in the case of power generation, though - little power going in means little power going out.
I love the bicimaquinas.