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If all of mankind's energy was supplied through solar panels would the effect be big enough to decrease the temperature (since light is converted in part to electricity)?
Technically, if you built enough solar panels in space, they would completely block the sun and massively decrease global temperature
Conservation of energy equation says otherwise.
Yes. If we built a giant circle of solar panels in space around the sun, it would cool the earth to the point it would be unliveable for humans.
wo:mankind FTFY
but serious answer: no. if humanity sources all its electricity through solar panels, these solar panels would cover <1% (IIRC) of earth's surface area, so the effect would be negligible.
Not directly. That electricity is converted to heat when it's used: All devices are space heaters, some just do other things as well. Even if not used, it would still be converted to heat by the panels. There's no getting around the conservation of energy.
In theory, we could send that power out into space as microwaves or light, but in practice the effect would be negligible. The direct heat output of every human activity is nothing compared to the sun: All the electricity generated on earth is around 3 Terrawatts, while the sun hits us with 200 Pettawatts, 66 thousand times more.
On the other hand, burning fuels releases gasses like CO2, which can traps sunlight and creates thousands of times more heat than the actual amount of power generated. If we stopped burning fuel, it would stop the current massive increase in global temperature, which would then slowly be reversed by things like the carbonate-silicate cycle.
but not all of it is converted back to heat. The energy used to do actual work is used for that. Some of it comes back out as heat
The work also becomes heat in the end.
That electricity is converted to heat when it’s used
a missing point is that fossil fuels use 3-4 watts of heat to make 1 watt of electricity or mechanical movement. Electric heat pumps can sometimes make 3-4 watts of useful enough (home) heat from 1 watt of electricity.
So lets paint the earth white to increase its albedo instead.
Thats been proposed lol. So many solutions instead of using "use less".
The worst part is that convincing people to use less is difficult even when it's something easy. Let's say for example that your dryer brakes and you need to replace it and up until this point you've been using either a standard resistive electric dryer or a gas dryer. Heat pump dryers are now readily available, of good quality, and use literally 1/4 the power of a resistive electric to do the same job.
If we could convince everyone to just only buy heat pump dryers from this point forward that alone would create a ridiculous drop in energy usage for drying clothes as it's a very energy intensive task. But people don't like things that are different and so convincing them to try it is very hard. I had to basically purchase one for my grandparents to get them to be willing to try it and now they love it but initially they were very strongly against trying
There's also a bunch of dumb but sometimes arguments. Take LED stop lights for example one of the biggest arguments against them is in places where it tends to snow every year they say oh well they aren't worth it here because when it snows they get covered and if you put a heating wire on them to melt the snow then you're not saving any power over the standard ones. But it's like hello rub a couple brain cells together unless you are somewhere where it snows 365 days of the year you're still saving the power whenever it's not snowing which is a pretty drastic amount of power across an entire city or state.
I could sit here and give examples all day but suffice to say convincing people to use less even when It ultimately results in a better end result for them is exacerbatingly difficult
No. If a watt worth of sunlight hits the earth, it's transformed into a watt of heat. If it hits a solar panel, it's transformed into some heat and some electricity, which is then used to power something that then transformed it into heat. The only solar energy that doesn't heat up the planet is the one that is reflected back into space, which, however, isn't much for solar panels.
However, if you use a watt of sunlight to power your phone instead of a watt of energy you got from burning coal, this watt of energy instead stays below earth and therefore doesn't heat up the planet. It also doesn't release co2, which would otherwise reduce the atmosphere's reflectivity, trapping even more sun heat on the planet.
So solar panels don't reduce the temperature by not allowing sunlight to heat up the planet, they decrease the temperature by replacing other stuff that would otherwise heat up the planet.
Solar panels aren’t 100% efficient though, so isn’t a bunch of it is reflected back in to space?
Isnt the energy also stored in batteries until ready to be used?
Yeah, so what? Eventually, it'll be heat.
co2, which would otherwise reduce the atmosphere’s reflectivity
Just to be pedantic CO2 absorbs bands in the infrared and reemits it, energy that otherwise could be lost to space. This is part of the reason you can't do infrared telescopes from earth.
https://news.climate.columbia.edu/2021/02/25/carbon-dioxide-cause-global-warming/
Water is an even more powerful greenhouse gas but fortunately the earth is cool enough for it to condense back out of the atmosphere. If temps got high enough that more evaporated than condensed then you'd get a runaway greenhouse effect and we'd be truly fucked.
Your comment in pictures:
Just note that the released energy of burning fossils (or nuclear) is orders of magnitude below what the sun does. It really is only the CO2 from coal (or CO2 and CH4 from natural gas, ...) that does the heating, since it acts like insulation.
Yeah, that explanation sounded off to me. CO2 and other greenhouse gases are the issue, not heat directly released from combustion. The sun is doing the overwhelming majority of heating. Carbon staying underground matters far more than watts staying underground.
Plants fixing carbon also converts energy to a form that isn’t heat, so I think we should count that along with reflection as a way that solar energy doesn’t become terrestrial heat.
Correct, but not only is it extremely little, this stored energy is also quickly released again after the organism dies.
quickly
Quick in geologic time. But this is what fossil fuels are, so it’s an order of magnitude or two different than the time in which generated electricity will be used.
And you’re right, it’s very small. Everything we know is pretty small, even combined. The amount of energy the sun imparts to the Earth every day equals what humanity would use over about 12 years at current levels.
Directly, as you phrased the question: No.
Indirectly: Yes. Because we would automatically stop burning fuels when we get all our energy from solar. That would decrease the temerature a tiny little bit.
But the temerature of the planet does not really depend on such actions. For example, the indirect effects of CO2 and Ozone in the atmosphere have much more powerful impacts - and still they can only change the temperature at the planet's surface (that's what our lives depend on). The whole of the planet is yet another thing.
Don't forget industrial heat. If we had infinite electricity for free everywhere there would still be fossil fuels burned for industrial heat. We need more technology to finish it like plasma torches.
No need to despair, the technology is being actively developed and a lot of the sub 600 Celsius temps have an electric solution now.
Industrial electric arc furnace temperatures can reach 1,800 °C (3,300 °F)
I was rather surprised to find out there was something like a smelter running on electricity (well industrial scale one). It will be a big deal if solar panels and wind turbines can be made exclusively with electricity from mining to final product.
Things are moving fast! Can't wait for them to figure out clinker for cement.
Don't forget industrial heat
Why? Is it different from "all of mankind's energy"?
I assumed you meant electricity since solar only makes that type of energy efficiently (and sub 100C)
Over 600 might be able to use focused sunlight? Like the tower in the middle of a solar farm? Though seems highly impractical to effectively laser that heat somewhere
Start reflecting sunlight back into space and increase the earth's albedo
but solar panels are black, does that mean it'll just make the earth hotter overall?
They appear black because they do not rreflect light but rather than absorb photons as heat they absorb them as electricity. This conversion means they do not get hot like a painted black surface does. In fact, solar panels are heat sensitive and become inefficient if too hot, so some have cooling on the back side or even water cooling.
It would decrease temperatures because no energy emissions brings hope that natural carbon sinks can come close to reducing atmospheric CO2 levels. Hydrogen replacing heat in iron/steel and cement could be enough. But it needs to be quick.
Solar panels provide shade which can cool the ground/water beneath them. At night, they release heat faster than ground, with less of it absorbed by ground relative to air and upwards to higher atmosphere.
google ai does say that more efficient solar panels get less hot. 2-5C over "standard panels", which I cannot source, but would assume its 2C per 5 %point extra efficiency.
In theory yes, but in practice no. Before we used fossil fuels (say 1000 years ago) the earth was on a slight cooling trend because a little organic matter still gets converted to coal. I can't find the amount, but IIRC it was something like enough for -0.1C every thousand years. That number is so small that even a tiny amount of fuel use would keep us even.
We are in the ending of an ice age.
In July 2018, the International Union of Geological Sciences split the Holocene Epoch into three distinct ages based on the climate, Greenlandian (11,700 years ago to 8,200 years ago), Northgrippian (8,200 years ago to 4,200 years ago) and Meghalayan (4,200 years ago to the present), as proposed by the International Commission on Stratigraphy.[6] The oldest age, the Greenlandian, was characterized by a warming following the preceding ice age. The Northgrippian Age is known for vast cooling due to a disruption in ocean circulations that was caused by the melting of glaciers. The most recent age of the Holocene is the present Meghalayan, which began with extreme drought that lasted around 200 years.[6]
Note: the 'cooling effect' didn't make the earth colder, it was just a cold lake that mixed with warm ocean water
Note 2: I'm not a geologist. I can hardly read this Wikipedia page
Assuming 25% efficiency, 25% of the sunlight will be converted into electricity. However, once that energy gets used later, most of it will be converted into heat, one way or another. The main way that it will decrease heat being released into the atmosphere is by replacing less efficient methods of energy generation.
For example, it you normally heat a house with a 90% efficient gas burner to generate 900W of heat on average, you are burning enough gas to generate 1000W of heat on average throughout the day. Lets also say the house gets 4000W of heat across its roof on average throughout the day. Thats 5000W of heat being released into the atmosphere total.
Lets now say you convert to solar panels and now get 25% of that energy from the sun converted to electricity, then into heat in the house. Electric heating is essentially 100% efficient, so you get 3000W of sunlight converted directly to heat in the panels, 1000W of electricity which is also turned into heat in the house = 3900W of heat + 100W of extra electricity (turned into heat elsewhere). The 1000W of gas gets eliminated completely.
It probably wont be anywhere near the numbers listed here and batteries will play a huge role in averaging out these numbers due to varying generation and use throughout the day. Additionally this doesnt account for things like cars and othergas based systems which wont / cant be replaced economically, other technologies like radiative cooling paint, and the fact that global temperatures will likely continue to rise due to the continued release of co2 and other gases. It might slightly slow things down though
Converting electricity generation to renewable alone isnt enough to reverse global warming, it would also require converting systens which use gas and other fossil fuels to electric
Nope, it only helps to not increase it further.
Yes, if the panels were in outer orbit, and mostly powering things outside our planet.
A little simplified energy cannot be destroyed only change form, each time it changes it loses a little bit of energy to heat. Over time that means all energy will become heat.
So the only way to not heat up the earth with energy is to either make sure it doesn't get to earth, or that we let it out.
Orbital solar cells could keep enough light from reaching earth to cool it, but releasing the energy dirtside would mostly cancel that out. So, we cover the earth orbit with panels and use them to fuel space things.
All of this requires more tech, a lot of resources and time to prepare though. And also a feasible way to store and use that energy in space. Maybe we shoot batteries at a moon base or orbital mining operation?