41–50 of 124 posts
I wonder if instead of the bolt itself we could capture the charge accumulation on a continuous basis That might be "easier" in some aspects
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?
Gasoline will burn for much longer so the energy will be released slower, so the peak will be much lower. And we perceive the peak light not the total amount of energy (see 1000 lumen stroboscope going 1 ms on - 999 ms off vs 1 lumen light turned on constantly).
Also gasoline will release more radiation in infrared part of the spectrum.
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?
The lightning finishes in microseconds. The flame front speed of well-mixed gasoline/air mixture is about 16.5 m/s (see https://en.wikipedia.org/wiki/Flame_speed ) so 6 microseconds to cross that 0.1 mm.
Seems comparable, right? But that's the entire length of the lighting bolt in microseconds, not just one patch. Plus, the 0.1mm calculation assumed only gasoline, not a gasoline/air mixture with a 12:1 compression. Any guidance from a real-life comparison would be affected by the diffusion speed of oxygen. If it takes significantly longer to burn the same energy then the intensity (energy/time) will be significantly lower.
In addition, the spectra are different. Have you ever seen a fuel-based camping lantern? They use a mantle to make the light significantly brighter. (See https://www.youtube.com/watch?v=F3rncxf4Or8 for details). This mean the visible light from burning fuel isn't a good guide for the amount of visible light which can be generated from the same amount of energy.
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).
Yes, and the Wired graphic was particularly misleading in that it showed, as I recall, multiple dollar amounts accumulating on per-session treadmill displays. On the other hand, it is possible to imagine lifestyles enhanced by various 10W contributions. 10W for heated clothing. 10W for a laptop. 10W average to power a several km electric bicycle or Aptera-size commute. And so on.
Eg. https://en.wikipedia.org/wiki/Harvesting_lightning_energy#:~...).
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".
I heard pro cyclists can reach up to 2kW. I managed to make 500W on a rowing machine for 5 minutes, but I'm a couch potato. I believe 400W is a normal rate for cyclists. When you are sitting, your body already produces about 100W of heat.
This reminds me of an old (misleading) graphic in Wired magazine suggesting that people on treadmills could be significantly reducing their electricity bills.
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.
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 liters is a unit of volume (length x length x length) and kilometers is a unit of distance (length). Hence, this efficiency metric is equivalent to L^3/L or just L^2. That is, the unit of vehicle fuel efficiency is a measure of area!
The area of what, you ask?
If you made the contents of your tank into a long thin stream of fuel as your vehicle moved along, then its cross section is the instantaneous fuel usage. You can imagine your car driving along, "sucking up" this long thin streamer of fuel as it moves.[1] The thicker this line of fuel, to more it needs for the same distance.
My car gets about 7L/100km, which works out[2] to just 0.07 mm^2, which is surprisingly thin!
[1] I can't take credit for this concept, I got it from XKCD's What If section: https://what-if.xkcd.com/11/
[2] https://www.wolframalpha.com/input?i=7+L+%2F+100+km+in+mm%5E...
TIL one gallon of gas is 120 lightning bolts, and the relative cost of energy between electricity and fuel is near equilibrium.