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A lightning bolt would be worth only about a nickel (2015)

engineering.mit.edu

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Re: A lightning bolt would be worth only about a nickel (2015)

#21

Post by benj111 »

agumonkey wrote: post #11
NoboruWataya wrote: post #3

Earlier quoted context omitted.

I've often wondered if it would be viable to run a gym where all of the equipment is designed to harness customers' energy to help power the building. I suspect it wouldn't make enough of a difference to be worth it but have never seen anyone run the numbers.

A dude did that, it didn't last long, but I'm still thinking about opening one. Just to avoid the double madness of powering lights and devices so people spend energy in the air :) Even if you don't generate much, at least your biomechanical efforts are used somewhere.

Surely it's triple madness if you're driving to a gym to go on the running / cycling machine.

Re: A lightning bolt would be worth only about a nickel (2015)

#22

Post by CodeBeater »

teraflop wrote: post #12
typedef_struct wrote: post #4

TIL one gallon of gas is 120 lightning bolts, and the relative cost of energy between electricity and fuel is near equilibrium.

To illustrate that even more vividly: if a typical lightning bolt is a few km long, the energy released is equivalent to detonating a stream of gasoline roughly 0.1mm in diameter (not much thicker than a human hair).

But the energy release from the gasoline would be much slower, right?

Re: A lightning bolt would be worth only about a nickel (2015)

#23

Post by agumonkey »

benj111 wrote: post #21
agumonkey wrote: post #11

Earlier quoted context omitted.

A dude did that, it didn't last long, but I'm still thinking about opening one. Just to avoid the double madness of powering lights and devices so people spend energy in the air :) Even if you don't generate much, at least your biomechanical efforts are used somewhere.

Surely it's triple madness if you're driving to a gym to go on the running / cycling machine.

Oh yes I forgot to mention this :)

Re: A lightning bolt would be worth only about a nickel (2015)

#24

Post by agumonkey »

akvadrako wrote: post #14
agumonkey wrote: post #11

Earlier quoted context omitted.

A dude did that, it didn't last long, but I'm still thinking about opening one. Just to avoid the double madness of powering lights and devices so people spend energy in the air :) Even if you don't generate much, at least your biomechanical efforts are used somewhere.

You could have them power fans or keep the lights on. Things that can use just a few watts.

each one yes, but if you have 20 persons averaging 100W, you can power a kettle :)

Re: A lightning bolt would be worth only about a nickel (2015)

#25

Post by Mordisquitos »

a9h74j wrote: post #2

This reminds me of an old (misleading) graphic in Wired magazine suggesting that people on treadmills could be significantly reducing their electricity bills.

Well, people with treadmills technically could significantly reduce their electricity bills—by running outside instead.

Re: A lightning bolt would be worth only about a nickel (2015)

#27

Post by praptak »

This looks like the opposite of a low hanging fruit. That fruit is hanging very high and on top of that it is very small and hard to get to the edible part.

Solar, wind, hydro, biofuel, geothermal, maybe even day-night temperature cycles - all of these look much more promising in the "free" energy department. Actually it's hard to think about a worse energy source. Earthquakes maybe? :-)

Re: A lightning bolt would be worth only about a nickel (2015)

#28

Post by ben_w »

joosters wrote: post #19
teraflop wrote: post #12

Earlier quoted context omitted.

To illustrate that even more vividly: if a typical lightning bolt is a few km long, the energy released is equivalent to detonating a stream of gasoline roughly 0.1mm in diameter (not much thicker than a human hair).

When you phrase it like that, it does feel like the quoted energy figure is too low - after all, lighting that tiny a stream of gasoline isn't going to illuminate the sky anywhere as bright as a lightning bolt. Perhaps the 'nickel of electricity' is what's remaining in electrical energy after all the rest has been used up as light, heat and sound across the sky?

Not in visible light, but I can easily believe it would be as bright if we could both see infrared and also if we made all that gasoline burn as fast as lightning propagates.

Re: A lightning bolt would be worth only about a nickel (2015)

#29

Post by anon_123g987 »

WJW wrote: post #15
jck wrote: post #5

Earlier quoted context omitted.

Let's say a person outputs 500W and we can somehow capture all of it. That would be 10cents worth of electricity in an hour. Note that these are very generous estimates, but it does demonstrate how silly the idea of trying to generate electricity by capturing exercise output is (in a purely economic sense).

500W is an extremely high number as well. Pro cyclists can reach up to 400 Watt in short bursts, untrained people typically can't maintain more than 100-150W for long. We really use quite a lot of energy when measured in how many humans it would take to provide that much energy "manually".

While it's true that the power of a human is not much (certainly not enough to power a house), but we have a lot of energy. Most of us carries at least 1 kg (~2 lbs) fat, which contains ~37 MJ of energy. For comparison, a stick of dynamite has ~1 MJ of energy.

https://en.wikipedia.org/wiki/Fat#Biological_importance

https://en.wikipedia.org/wiki/Dynamite#Form

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