9 ms·
A lightning bolt would be worth only about a nickel (2015)
- whoomp12342 4y agoif so little power, how does it fry a tree?
- deleted 4y ago[deleted]
- trelane 4y agoIt's not so little power, it's so little _energy_ (power over some period of time). It's a crap-tonne of power, just over a _very_ short period of time. And yes, power is what fries the tree: https://en.wikipedia.org/wiki/Joule_heating https://en.wikipedia.org/wiki/Joule_heating
- whoomp12342 4y agomind=blown. I never considered the time factor
- typedef_struct 4y agoTIL one gallon of gas is 120 lightning bolts, and the relative cost of energy between electricity and fuel is near equilibrium.
- teraflop 4y agoTo 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).
- joosters 4y agoWhen 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?
- ben_w 4y agoNot 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.
- ajuc 4y ago> lighting that tiny a stream of gasoline isn't going to illuminate the sky anywhere as bright as a lightning bolt. 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.
- eesmith 4y agoYou are comparing two different time scales and two different spectra. 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 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 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.
- ladyattis 4y agoYou have remember that most of the energy in a storm is more to do with its exchange of air masses. It's more like a boiler than a dynamo. So it doesn't surprise me that lightning in practice isn't energy dense. But figuring out how to capture the energy generated seems like a fun experiment just to see how far we can go with material science than anything else.
- raverbashing 4y agoI wonder if instead of the bolt itself we could capture the charge accumulation on a continuous basis That might be "easier" in some aspects
- londons_explore 4y agoIt's really hard to do because within the cloud each water droplet contains a tiny bit of charge. The air between them is an insulator. The cloud is many cubic miles. So to extract the charge you either need to touch every droplet, or make a spark between each droplet and a neighbouring one (which is what happens during a lightning strike).
- joosters 4y agoLightning-powered bitcoin mining is obviously the next big thing for green energy! Now you need a double helping of luck - first that you get struck by lightning, and second that your miner guesses the right hash to make a block. But maybe the two somehow combine? After all, people who survive a lightning strike are said to be so lucky that they should buy a lottery ticket... so following this logic, lightning powered mining would be extra efficient! Now I'm off to patent my new PoS invention - proof of strike :)
- usrn 4y agoI know a number of people who have been struck by lightning. It seems like you've got a decent chance at survival if you're not touching anything metal.
- sebzim4500 4y agoDo you know a lot of people who stand on top of tall towers during storms? Otherwise, unless you know tens of thousands of people there is very little chance of knowing multiple people who have been struck by lightning.
- elif 4y agoI also know two people, my mother and a leader at my boyscout camp. Both wearing rubber-soled shoes and survived without needing hospitalization. Maybe birthday paradox or something similar at play? Only 64 commenters but appears more common than your belief would indicate. I bet if you are a regular golfer you would know more, and if you spend 100% of your time in a concrete jungle you would know less.
- naavis 4y agoThe rubber soles don't mean much, though. The electric current just passed through kilometers of insulation (air). It doesn't care about 2 cm of rubber.
- csours 4y ago
- Gibbon1 4y agoThe energy needed to bring a teapot to boil is enough to fling a nickel into orbit.
- yellowapple 4y agoRegrettably, I doubt the average home has a stove hot enough to boil teapots.
- visarga 4y agoI was curious, it comes about 310Kj if you ignore friction, or about the same calories as you gain by eating an apple.
- koheripbal 4y agoOnly if you ignore friction.
- coldtea 4y agoI call BS. A lighting bolt generates at least 1.21 gigawatts, which is good for many purposes...
- selljamhere 4y agoIt’s also pretty easy to figure where it will strike. Just wire up the ol’ clock tower.
- dzhiurgis 4y agoFor 0.2 seconds which is wolfram alpha says is 67.2 kWh
- praptak 4y agoIf you really mean gigawatts (unit of power), then you have to multiply it by the time period when this peak power is reached to get the energy output. Lightning bolts have very short durations, tens of microseconds. Let's be generous and give it 1 millisecond. 1 millisecond times 1 gigawatt is 1 million joules, which is the estimate that the article gives.
- peterpost2 4y agoWoosh, he is making a back to the future reference
- ww_wpg 4y agoWell, today I learned something about physics and pop culture.
- martin_a 4y ago> Lightning bolts have very short durations That is why you have to hit the cable at a very specific time. It's not that hard.
- trelane 4y agomartin_a, or marty_m? Hmmmm....
- praptak 4y agoThis 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? :-)
- londons_explore 4y agoTo say this another way... A lightning bolt would have to hit the average US home every 12 minutes to keep everything powered (assuming perfect conversion and no losses)
- londons_explore 4y agoSome websites suggest the average lightning bolt has 5 GJ of energy, which is 5000x what this page quotes. I think someone has done a math error. Eg. https://en.wikipedia.org/wiki/Harvesting_lightning_energy#:~:text=A%20single%20bolt%20of%20lightning,in%2038%20gallons%20of%20gasoline https://en.wikipedia.org/wiki/Harvesting_lightning_energy#:~...).
- abujazar 4y agoAnd this is why Nikola Tesla died poor.
- andrewla 4y ago> The average lightning strike contains about 1 million joules, enough energy to fry the founding father in his boots. “The typical house in the U.S. has 100 amp service or about 28 horsepower,” says Kirtley. Boy do I get frustrated when using compatible units without conversion. The unit that I hate more than any other unit in the universe is the KwH, which is dimensionally equivalent to the Joule, so I don't understand why we don't just use that instead. "The typical house in the U.S. has 100 amp service or about 28 horsepower" -- seems that it would be way more interesting to say that "the typical house has 100 amp service at 120V, which means 12,000 J/s". The way the original quote is phrased (and the introduction of horsepower of all things) seems insane to me; the clarification adds zero value. You still haven't addressed the main question, which is "is the energy in a lightning bolt a significant amount of energy compared to household usage". For all I know 28 horsepower is 1,000,000 J/s, so a lightning bolt would only power a house for a second. EDIT: as many commenters have pointed out, apparently most houses get 240V service, so just double the number above. Still, this is easily fixable, and the main point is that horsepower does not add any value to this discussion.
- themitigating 4y agoThe typical house has 240 volt service in the US (two legs of 120v). I would also say a decent number of homes have 200amp as well
- samatman 4y agoThis is true, but I'm fairly certain that the amps of available power are calculated on a 120v basis, a 10 actual-amp washing machine would use 20 accounting amps at maximum power.
- sokoloff 4y agoThe rating of a service (and by extension, the main breaker) is available at 240V. It's true that if all of your 200A load is consumed on a single leg, with zero amps consumed on the opposing leg, that you would only be able to consume 200A * 120V nominal or 24kW, but if the load is balanced, you can pull 200A @ 240V nominal or 48kW.
- david_draco 4y agoTherefore, one could easily generate lightning with equal destructive power? Why is it not used yet in war (airplane to ground) or for entertainment (airplane to airplane)?
- banannaise 4y agoNot really. Think lasers - they're not expensive because of the energy output, they're expensive because concentrating energy output is far more difficult than simply obtaining and outputting energy.
- whoomp12342 4y agoaiming is a tough thing
- greenbit 4y agoA megajoule in a microsecond, that's a terawatt impulse with decidedly RF personality. Anything that could generate that would be as big as anything that could capture it. Not exactly nimble enough to weaponize.
- daniel-cussen 4y agoTesla coils, arc lamps.
- deleted 4y ago[deleted]
- photochemsyn 4y agoFun facts & questions from Feynamn lectures: > "On an ordinary day over flat desert country, or over the sea, as one goes upward from the surface of the ground the electric potential increases by about 100 volts per meter. Thus there is a vertical electric field E of 100 volts/m in the air. The sign of the field corresponds to a negative charge on the earth’s surface. This means that outdoors the potential at the height of your nose is 200 volts higher than the potential at your feet! You might ask: “Why don’t we just stick a pair of electrodes out in the air one meter apart and use the 100 volts to power our electric lights?” > "Although the electric current-density in the air is only a few micromicroamperes per square meter, there are very many square meters on the earth’s surface. The total electric current reaching the earth’s surface at any time is very nearly constant at 1800 amperes. This current, of course, is “positive”—it carries plus charges to the earth. So we have a voltage supply of 400,000 volts with a current of 1800 amperes—a power of 700 megawatts! With such a large current coming down, the negative charge on the earth should soon be discharged. In fact, it should take only about half an hour to discharge the entire earth. But the atmospheric electric field has already lasted more than a half-hour since its discovery. How is it maintained? What maintains the voltage? And between what and the earth? There are many questions." https://www.feynmanlectures.caltech.edu/II_09.html https://www.feynmanlectures.caltech.edu/II_09.html
- jcims 4y ago'The Action Lab' channel on YouTube did a little experiment with this - https://www.youtube.com/watch?v=0VgqRigZAHA https://www.youtube.com/watch?v=0VgqRigZAHA
- 1970-01-01 4y agoA lightning bolt is literally the opposite of clean power. Clean in this sense is lack of electrical noise. Random.org have created their RNGs using lightning strikes. https://api.random.org/features https://api.random.org/features
- dehrmann 4y agoAt one point, I realized that lightning is the breakdown of the dielectric material of a capacitor. This means you harvest electric by draining it with a large sheet or web of conductors at cloud level. No idea how well this would work or how much energy there is to collect, and it would be pretty impractical.
- giardini 4y agoBut worth a fortune if you can put it in a small package deliverable on command (i.e., a weapon).
- a9h74j 4y agoThis reminds me of an old (misleading) graphic in Wired magazine suggesting that people on treadmills could be significantly reducing their electricity bills.
- NoboruWataya 4y agoI'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.
- jck 4y agoLet'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).
- a9h74j 4y agoYes, 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.
- Flashtoo 4y agoThis isn't exactly what you are talking about, but this art/concept for self-powered student housing came to mind: https://www.humanpowerplant.be/human_power_plant/human-powered-student-building-plans.html https://www.humanpowerplant.be/human_power_plant/human-power...
- benj111 4y agoIn their defense this could be seen as a type of gamification. Ultimately you can put any dollar amount on a kWh of electricity. It's the kWh generated that matters. Not saying it's a good defense though.