As for solar panels I think the word you're looking for is "albedo"
Off the top of my head I think it's close to earth's natural albedo anyway. Or even if it is a lower number and more energy/heat is absorbed it's so negligible. Only the tiniest fraction of the earth's surface would be/are covered in panels
I’m not exactly sure of the context of the question.
Electricity plants use the excess heat for district heating. It isn’t just wasted. If we could suddenly stop using coal or other combustibles for electricity production, we’d still need to produce energy for heating.
Transport is different though. Gasoline engines are highly inefficient and produces a lot of excess heat that isn’t used even when the heater is on full blast. It’s not much in comparison to power production though, so while it will be more efficient to drive and heat a car by electricity, excess heat from cars isn’t really an issue in itself. It’s the pollution that is the main issue.
Well, my thinking was that if the produced heat was not negligible, then it would be cooler (literally) to use energy for heating which is being pushed into our atmosphere already anyways, rather than actively unearthing additional energy.
Its not the question you asked, but Nuclear plants can raise the temperature of the bodies of water they use for cooling nuclear plants. Additionally climate change is reducing water availability needed for nuke plants which is something I don’t hear the nuclear advocates talk about when we’re facing a dryer and hotter future. We’ll have to start turning off nuclear plants right when we need them.
This is already happening occasionally in the last decade:
Lochbaum analyzes reports from the NRC showing when nuclear plants scale back generation because of warm water.
In June, nuclear plants in Georgia, South Carolina and Pennsylvania scaled back their generation multiple times because of hot temperatures warming their cooling water. The Limerick power plant on the Schuylkill River near Philadelphia has scaled back because of high temperatures frequently over the past decade, according to the reports.
The Dresden and Quad Cities plants in Illinois had to scale back because of high water temperatures multiple times over the past five years. The Duane Arnold plant in Iowa and the Monticello plant in Minnesota also reported scaling back generation because of temperatures.
Yeah, I’m from Germany and we experienced this second-hand in 2022, when lots of French reactors were either in reparation or had not enough cooling water during the drought, so France imported tons of power from us and drove up prices.
This all happened on top of inflation and the Russian conflict, so hard to say how much it actually influenced prices, but those were quite high in the end, so presumably not nothing.
Without this happening, I probably wouldn’t have been acutely aware of nuclear producing much heat. Obviously, they do have those massive cooling towers and I have read before that it’s just another form of steam power, but you know, never properly thought about it.
So, in one hour, the Earth receives more energy from the sun than us humans generate in an entire year. If we took all of the energy we generated over a year (and not just the waste heat) and converted it into heat, we wouldn’t even be adding half of one percent to the system. Our direct contributions to the system are minuscule. The problem is we’re pumping out green house gasses like there’s no tomorrow. And those directly increase the amount of solar energy the Earth retains. And when we start keeping 1 or 2 more percent of that insane amount of solar energy, it adds up really, really fast.
Not that it changes things much, but pretty much that entire 163,000 TWh ends up as heat, not just the waste. Pretty much the only energy that doesn’t is light and other transmissions that get radiated into space.
Yes, it’s negligible. Before considering atmospheric attenuation, every day something like 15,000,000,000,000,000,000,000 Watts (15 Zettawatts) of the sun’s power reaches the earth. SOURCE
So enough power hits the earth in a second to power the human population’s activities for many months at a time.
You would think that’s enough to put into perspective how bad energy trapping atmospheric emissions are, but nope.
Humans generate 4,000 terawatt hours of electricity in a year. The sun dumps nearly that much on earth in 1 minute. That’s a 6 order of magnitude difference. So I’m going to assume that human heat generation is probably negligible.
The greenhouse gas “problem” is necessary to survive. If the greenhouse effect didn’t exist, neither would life as we know it.
The issue with combusting non-renewables is that that energy used to be sequestered away from the carbon cycle, effectively allowing for a balance without too much overall disruption (certain natural events notwithstanding).
So now, with all this stored away, not-part-of-the-carbon-cycle carbon being burned up, we’re adding more to the carbon cycle, disrupting it, and causing a new higher thermal equilibrium (which has yet to be reached due to geological time scales). Side note: water is a better greenhouse gas than methane or carbon, but it’s accounted for.
Because the greenhouse effect still exists, and we’re adding more greenhouse gasses, the greenhouse effect will not allow heat to transfer to space as easily.
With solar being “captured” by a black roof, that would be mostly negligible, as a portion of that energy will potentially radiate away during the capture process. However, with more greenhouse gasses being dumped into the atmosphere, that radiative cooling will become less viable as time goes on, as it too will stay largely captured.
We need to reduce greenhouse gas emissions, otherwise it’ll cause a runaway effect. That part might be too late.
That’s one hell of an assumption. It’s not gonna break down equally across the entire spring. Whatever the weakest point is will eventually wear away first and cause it to break because of all the tension in it.
Even if it could dissolve equally across the entire spring, the outer parts would go first and it eventually will dissolve away from the things holding it in place and release that tension. If it doesn’t just break due to the dissolving metal weakening the structure while still under tension.
I feel like to get the meat and potatoes of the question a better way of asking would be what would happen to the potential energy if the spring was instantly vaporized, like by a Star Trek phaser.
Assuming the spring dissolves perfectly (no breakage, just complete disintegration)
I think, eventually, this assumption breaks down. As the metal is dissolved away, the internal stresses in the spring will become greater than the remaining metal can hold, and the spring will break.
If the spring does eventually break, it will be a weaker spring since a lot of material is gone. The potential energy of a spring at the breaking point would be different than the original spring. So I guess I could rephrase the question, what happens until that point? Does it get let go as heat?
Fair enough, thinking about it at a microscopic level, individual molecules/atoms of material will be pushed into positions where they are being repelled from other atoms/molecules via electromagnetic forces. Those forces won’t go away as the chemical reactions happen; so, I would guess that the answer is kinda the same as it is at the macroscopic level. When the bond which holds an individual atom in the lattice of the material is broken, those electromagnetic forces would push the resulting molecule away. So ya, it becomes heat.
I would imagine that as the tiny bits of the spring are released from one another, the stored energy would be released as a small force within the acid. That is, even if the reaction was perfect down to the molecular level, the new molecule combination would be “launched” away from the spring more vigorously than if the spring weren’t compressed. So you’d end up with the acid being “stirred” a bit by the reaction.
The potential energy of the spring is “stored” in individual molecules that are pushed into some configuration that they don’t quite want to be in, and they exert force on each other trying to push themselves back apart / back together into being the way they like. As the spring disintegrates, you could model those individual forces, and molecules exerting force on each other would release it into kinetic energy one by one or in groups, as the spring gradually lost its integrity to exist as a singular entity.
(I think that in practice, metals are made of grains, big groupings of molecules which stay pretty much as rigid bodies unless something really crazy happens, so most of the potential energy is force of the grains wanting to go back into their preferred arrangement in relation to other grains. I.e. not in practice at the level of molecule to molecule. But I’m not 100% on that part.)
Depends. If the antennas were resonant dipoles placed some fraction of a wavelength away from each other (1/4 wave away), you may get some cancellation of the signal.
Look up the “yagi uda” antenna, it’s the classic rooftop tv antenna. The elements are spaced by fractions of a wavelength to achieve directivity. One single element is driven, the others are just resonant lengths of wire.
People are answering what you asked but what you probably mean is in a 2d world where two antenna are perfectly in line with the transmitter will the first absorb some of the signal - yes it will, just like two wind turbines in a line it’s absorbing the energy from the medium and using it to do work.
It’s not always so simple, it might spit some of if out too if it doesn’t have anywhere else for it to go and it’ll do this in a certain pattern which can, depending on the distance and arrangement ,increase the signal received by the second one. This and similar principles are why you see so many odd shapes for antenna designs such as the many bars on a TV antenna which make it more directional.
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