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Exercise bike that can store 2KWh of electricity (mastodon.social)

submitted 6 months ago by poVoq@slrpnk.net to c/technology@slrpnk.net

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This is an industrial designed exercise bike from Lithuania that can store 2KWh of electricity generated by your own exercise.

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[–] Septimaeus@infosec.pub 17 points 6 months ago* (last edited 6 months ago) (1 children)

3,442 Calories (14,388 kJ) is required to generate 2 kWh at a (generous) overall storage-work-storage efficiency of 50%.

For comparison, that is roughly:

one pound of body fat
a marathon
a full day of cycling

[–] qjkxbmwvz@startrek.website 4 points 6 months ago (1 children)

Rule of thumb efficiency of humans is about 25%, which is about the kJ to Calorie conversion, too

so 14kJ of energy output burns ~14,000 Calories.

[–] Septimaeus@infosec.pub 3 points 6 months ago

True, I only included kJ equivalent because some countries use kJ on nutritional panels instead of Calories. Actual conversion rate of human energy stores to usable power is, at a guess, more like

Calories * 0.25 * 0.6 * 0.8 - dt

where t is time, d is the self-discharge rate of the battery, 0.6 is the efficiency of the generator, and 0.8 is the efficiency of the battery.

So, user better eat their wheaties.

[–] sabreW4K3@lazysoci.al 10 points 6 months ago* (last edited 6 months ago) (1 children)

Love things like this, but at 3.500€, that's a massive ask. Hopefully the concept catches on.

[–] Glimpythegoblin@lemm.ee 8 points 6 months ago

2kwH is worth about $0.18 here. I'd have to charge it ~19,500 times to offset the cost in electricity.

[–] Sibbo@sopuli.xyz 6 points 6 months ago (1 children)

A fun toy. But a normal exercise bike already converts the energy to heat. This heat then warms up the apartment.

Of course, with electricity, a heat pump for heating or cooling could be used, which is more efficient. But it's not like the energy remains unused with a normal exercise bike, as long as it is cold outdoors.

[–] sukhmel@programming.dev 3 points 6 months ago

But sometimes it's hot outside 😓

[–] rickyrigatoni@lemm.ee 3 points 6 months ago (1 children)

I've been wanting this for years. But maybe not at that price.

[–] poVoq@slrpnk.net 4 points 6 months ago* (last edited 6 months ago) (2 children)

As it seems to double as a balcony solar inverter if you add some PV pannels the price seems to be not so bad. A 2KWh LiPO4 battery, charge-controller and inverter alone will cost you at least half of the asking price.

[–] AmbroisindeMontaigu@kbin.social 4 points 6 months ago

Maybe making a bike for half the price that can just plug into an existing inverter / battery would be more versatile then.

[–] rickyrigatoni@lemm.ee 2 points 6 months ago

That definitely changed things a bit there.

[–] issastrayngewerldkbin@kbin.social 3 points 6 months ago

They need to put these in all of the gyms in the cardio equipment. Just think of the power they could store.