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

submitted 5 months ago by [email protected] to c/[email protected]

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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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[–] [email protected] 0 points 5 months ago* (last edited 5 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

[–] [email protected] 0 points 5 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.

[–] [email protected] 0 points 5 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.