A lightning bolt would be worth only about a nickel (2015)(engineering.mit.edu) |
A lightning bolt would be worth only about a nickel (2015)(engineering.mit.edu) |
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.
Strictly speaking, 240V. Normal electric service in North America is 240V split-phase, with the distribution transformer's center tap grounded and serving as the neutral line. We normally only use the full 240V for heavy loads like electric ovens, arc welders, large air conditioners, and such.
Large buildings often use 208V three-phase power, yielding 120V phase-to-neutral, and large commercial lighting installations are often 277V taken from one leg of a 480V three-phase feed. Voltages greater than 240 are not permitted in residential service, and I wouldn't be surprised if phase-to-neutral > 120 is out as well for homes.
Are you running a 100W load (0.1kW) for an hour? That's 0.1kWh. Running it for ten would make a whole kilowatt hour.
This allows for easy calculations of how much something is going to cost in electricity, and the units are such that it's easy to do the math in your head.
In the end there's no practical utility to this. We just pretend that we're living in a world where you get a 100W light bulb and know exactly what it will cost you, and not a world where half your bulbs claim to be 100W but are actually 14W with 100W-incandescent-equivalent and such.
Can we wire that in a way to would allow installing .uk or .de Schuko Type-F plugs?
It would be funny (and weird!) to have 220V available on a european socket for say a desktop equipped with a 1.5kW PSU for the upcoming Nvidia 4090 :)
It's still rare enough you have to ask ahead of time if you want it for any building you get into, but in some major metro areas it has gone from "you have got to be joking" to "sure, let me check on that".
Now if only I can find a reliable, durable three-phase solar inverter...
kWh/yr is worse. It's just watts but obfuscated. Gets used for appliances.
Horsepower is clearly insane though, I have no idea why you'd bother.
Regardless, head-math or otherwise, the vast majority of people will never do this calculation at all, except maybe to weigh the relative power consumption. And if they do the math, having a calculator and having all the units be compatible with each other (so just a natural conversion of W to J/s) is totally fine.
As far as I can see, nowhere in the article does it give enough information (even if you take into account unit conversions) to say how much of a house's electricity would be supplied by a lightning bolt.
Example: a 100 amp house circuit running maxed out in the US will use 12 kWh per hour, or 0.2 per minute. Try doing it in your head with joules. Annoying right?
12 kWh / h? Am I a crazy person? No. I'm working on a useful problem.
> "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."
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 :)
Otherwise, unless you know tens of thousands of people there is very little chance of knowing multiple people who have been struck by lightning.
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...
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?
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? :-)
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.
That is why you have to hit the cable at a very specific time. It's not that hard.
For example the flash you have/had on standard camera (not smartphone who have LEDs, but the standard compact camera that is just a camera) is about 1kW!!
But this 1kW you have it for about 1ms (milisecond!!). It seems to last longer because the light gets “burned” into your eye.
Eg. https://en.wikipedia.org/wiki/Harvesting_lightning_energy#:~...).
That might be "easier" in some aspects
And yes, power is what fries the tree: https://en.wikipedia.org/wiki/Joule_heating
Things like laptops and some desktops could be easily powered by bicycle, though. I managed 220W for 30 mins, and could probably idle 50-75W for hours, which is more than enough for multiple laptops.
Some city noticed changes in consumption when new houses had meter installed on ground floor rather than in the basement.
They're advertised as saving energy which I think is a bit misleading as it's only based on this phenomena
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).
Even if you don't generate much, at least your biomechanical efforts are used somewhere.
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.
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.
It was probably the worst energy scheme they could have spent the estimated £16bn on. That much in insulation would have slashed domestic heating costs, but as ever that's a much less sexy project.
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.
Instead, let's just use Joules everywhere. Easy peasy. Why are my batteries rated in Ah -- it's not like they're providing a variable voltage source; just give me Joules.
I know this is a ridiculous hill to die on, but I will die on it!
They are, technically. https://www.batterypowertips.com/how-to-read-battery-dischar...
Probably doesn't matter though. :)
That said, it's your house, so you may be able to do that in some places. I've thought about it myself, so I can get a euro tea kettle.
That said, the power will still be at 60Hz not 50, which will matter for some uses (e.g. impedances will change).
There are definitely 240V for higher power usage (because they will need half the current for the same power with double voltage, and current (current density, technically) is what causes joule heating and melts wires/ starts fires.
The sockets will be incompatible with Euro or UK sockets. You could change the socket to a euro socket, bit the frequencies will be wrong for euro or uk devices (60Hz in the us, 50 in europe & UK.) This may or may not be important depending on what you're hooking up to it (understand that impedance and other electrical things are a function of frequency). The safest option would be to get something to convert the power (there seen to be products to do that) and put _that_ behind the Euro or UK outlets.
And wasn't it Mumford who observed that given the time it takes to earn the money to buy a car, on average it can be faster to walk than to drive.
Not a toy example. That's exactly how I estimate energy consumption for off the shelf devices. And for battery life (W*h but still).
> 100W light bulb and know exactly what it will cost you, and not a world where half your bulbs claim to be 100W but are actually 14W with 100W-incandescent-equivalent and such.
If you've lived with lighting you're responsible for, you've replaced bulbs. You know the different technologies and the packages say how much power they require.
Last year I switched off my fully-functional 2008 workstation (a lovely Fujitsu Celsius W370 on OpenBSD, a furry joy) because of such an upper bound difference (300W vs 65W for the ThinkCentre that hides among the books on my desk's side).
This sort of works in a similar way with light bulbs as well. Although lumen would be the appropriate unit for luminosity, the packaging uses wattage to indicate luminosity.
Although lumens and Watts are correlated, they aren't dimensionally equivalent as Joules and Watts are (CMIIW).
That "100W" on the package an electrically 14W bulb simply means "it's only using 14W, but shines like a 100W bulb, go ahead, BOGOF".
A watt to watt comparison is fine. Why hours? I can tell you right now that the big one uses ~4.5x the power. Is it really that much easier to convert the time you're using the device to seconds? If you're going to multiply by the electricity cost anyway, might as well break out the calculator one step early.
Where i live, the pricing is based on the amount of energy "consumed" during a month. plus we use 220v.
i use the kwh extensively, my induction cooker is rated at 1300Watts so i know by running it for 1 hour i am consuming 1.3kwh.
my monthly "consumption" before installing a 5kwh solar on-grid used to be around 300Kwh during summer months so over time i have learned to "reduce" my monthly usage, aka kwh by reducing my electric hot water geyser( going to solar water heater) (2kw geyser).
the kwh is definitely a good indicator for me
All of that math can be done in your head too, if you're willing to approximate the number of hours in a day to 25 and the numbers of days in a month to 30.
Why would I be running the light all day? The assumptions being made here are unrealistic enough that the answer becomes meaningless. The realistic question here, "how much money would I save by switching from a 100W incandescent bulb to a 14W LED bulb" is not helped by any of this kWh nonsense.
A joule is just a watt second instead of a kilowatt hour, and the 3600 factor (seconds per hour) is really annoying to use in mental math.
It's a lot more than that. Even a fit (healthy, but not necessarily peak athletic shape) adult man will have about 15% body fat, 20% for a woman.
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 hugely depends on body weight / gender / training levels etc., body weight being a big deal since that’s what you’re transporting. So the other way folks measure output is W/kg of body weight.
A beginner adult male will be in the 100-200W zone, around 0.5-1.5 W/Kg. Usually anyone can train themselves into the 200-300 (3-4 W/Kg) zone which is the recreational pace - the groups of cyclists you see on the road. Beyond 300 ftp (150lb body weight) (4-5 W/kg) you’re reaching race pace. The ones you see on screen have upwards of 5-6 W/Kg FTP output. They obviously have other constraints around putting this output at the end of a 200km ride for 20 mins etc as well, which makes it extra hard.
Finally we come to the KW numbers - all these folks have two kinds of muscles (fast twitch and slow twitch). The sprinters are saddled with a higher proportion of the kind of fibers that can allow huge spurts of power - they put out about 1000-1500W for about 5-10s. These are probably what you’re thinking of. This is pretty much an end of ride (or a sprint section) empty your tanks effort.
Semi related tidbit: track cyclists are a middle kind of beasts here: they put 600-1000W for a couple of minutes but don’t have to worry about riding 200kms to get there.
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.
Based on Ali Express, heated clothing (5V power in a pocket) is popular enough in China.
Not saying it's a good defense though.
> If you're going to multiply by the electricity cost anyway
I don't usually convert to money. If it's a linear cost per kWh, then I can deal with that at the end or, more likely, don't actually really care.
The _actual_ cost you pay is often tiered anyway, so who knows what the price _actually_ is until you have the whole month's worth of power usage finalized. And then it's not clear what I could account to what tier.
> might as well break out the calculator one step early.
Bold to assume I use a calculator much.
But that was mostly because that workstation, albeit lovely, had a very long boot process.
The ThinkCentre boots in under a minute, so I actually end up only booting it when needed.
(Some of my work can be done offline, and I jump at every opportunity to `halt -p` and be in the quiet offline space/state.)