The discussion revolves around the fate of energy absorbed from the sun when solar panels are used to power electric cars. Participants explore concepts related to energy conservation, heat generation, and the implications of various energy production methods on Earth's temperature.
Participants express a mix of agreement and disagreement regarding the implications of energy absorption and its effects on Earth's temperature. Multiple competing views remain on how different energy sources contribute to heating and the role of renewable energy in this context.
Participants discuss various assumptions about energy conservation, the definitions of isolated systems, and the complexities of energy transformations, which remain unresolved.
Heat, the answer is almost always heat. There's some sound production as well from the motor, but it'll be heat lost in the wiring, heat transferred to the air and any moving part etc. Some will also be radiated away, but most of this will be in the IR part of the spectrum.Baconfish said:Ok, we had a discussion in class: If we build solar panels all over the Earth's surface we can collect a good amount of energy. If we use this energy to power el-cars where does the energy end up? The energy law states that no energy can be lost from a system.
From an isolated system. If the Earth was isolated, the Sun's Energy wouldn't get here in the first place, would it? Some energy leaves the Earth on the same way as it got here, as radiation.Baconfish said:The energy law states that no energy can be lost from a system.
Baconfish said:So if kinetic energy usually ends up like heat this means that power production like fission and fusion (in the future :) ) will heat up the planet?
Then no more energy would come in.Baconfish said:Yes i just thought about the Earth as a isolated system afther the energy was taken in.
Why would it come back? Some of it escapes into space.Baconfish said:Ok so basically we would heat up the Earth since the IR radiation would come back down again.
But i should count out wind, wave, water and all kinds of renewable energies right? Since they are in a natural cycle. Or maybe not, as the water in a reservoar for example would naturally not end up as heat, but rather move around some rocks on the natural path down the mountain?Nugatory said:Yes, although it is a good exercise and somewhat fun to calculate by how much. Try it!
Google will give you some decent values for annual energy production and the mass of the earth, and you can make some reasonable order of magnitude estimate for the specific heat of the earth.
If it moves rocks down, then even more potential energy is released and converted to heat.Baconfish said:the water in a reservoar for example would naturally not end up as heat, but rather move around some rocks on the natural path down the mountain?
Oh ye! So the i probably should count them out if I am interested in a net heating of the earth. I should only count fission and solar.A.T. said:If it moves rocks down, then even more potential energy is released and converted to heat.
Baconfish said:But i should count out wind, wave, water and all kinds of renewable energies right? Since they are in a natural cycle. Or maybe not, as the water in a reservoar for example would naturally not end up as heat, but rather move around some rocks on the natural path down the mountain?
So if kinetic energy usually ends up like heat this means that power production like fission and fusion (in the future :) ) will heat up the planet?
Angular momentum is conserved. If rocks move down (inwards), then the angular velocity of Earth and rocks increases by a tiny amount, and the angular kinetic energy of Earth and the rocks increases.A.T. said:If it moves rocks down, then even more potential energy is released and converted to heat.
That doesn't contradict what I wrote, does it?rcgldr said:Angular momentum is conserved. If rocks move down (inwards), then the angular velocity of Earth and rocks increases by a tiny amount, and the angular kinetic energy of Earth and the rocks increases.
Hehe that's really cool to think about :) so easy to change the world :prcgldr said:Angular momentum is conserved. If rocks move down (inwards), then the angular velocity of Earth and rocks increases by a tiny amount, and the angular kinetic energy of Earth and the rocks increases.
Yes. They are commonly called 'heat islands'.Baconfish said:This maybe explaines one other thing: Many times i´v wondered why often in cities its wet while its laying snow just outside it eaven though the topography is the same, so its probably just waste heat!
rcgldr said:Angular momentum is conserved. If rocks move down (inwards), then the angular velocity of Earth and rocks increases by a tiny amount, and the angular kinetic energy of Earth and the rocks increases.
I'm wondering how much of the decrease in GPE goes into the increase in angular kinetic energy versus heat.A.T. said:That doesn't contradict what I wrote, does it?
Baconfish said:This maybe explaines one other thing: Many times i´v wondered why often in cities its wet while its laying snow just outside it eaven though the topography is the same, so its probably just waste heat!
Aha so basically removal of trees and lots of black asphalt..CWatters said:
Actually, if you look a the heat map I posted, it seems that concrete (buildings) is hotter than asphalt (roads).Baconfish said:Aha so basically removal of trees and lots of black asphalt..