Does nuclear power contribute to global warming?
Discussion
All energy ends up as heat. But nuclear power is the only human power source that unlocks energy from the the destruction of mass from the bonds in the atom.
In other words, the more uranium we use, the more total heat output into the atmosphere increases? It's not a closed system?
All other energy sources are closed systems, eg eventually more trees grow, die, get compressed back into coal etc. ?
Genuine question, is not nuclear (fission and fusion) going to contribute to an increase in temperature of the planet? Or does excess heat bleed off into space? In which case global warming isn't a thing anyway?
In other words, the more uranium we use, the more total heat output into the atmosphere increases? It's not a closed system?
All other energy sources are closed systems, eg eventually more trees grow, die, get compressed back into coal etc. ?
Genuine question, is not nuclear (fission and fusion) going to contribute to an increase in temperature of the planet? Or does excess heat bleed off into space? In which case global warming isn't a thing anyway?
The energy from the nuclear reaction goes to heat water which drives turbines to generate electricity. Most nuclear power plants are around 30-35% efficient, which means that maybe 70% of the energy is not captured, which indeed will be released into the environment as heat.
Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
deckster said:
The energy from the nuclear reaction goes to heat water which drives turbines to generate electricity. Most nuclear power plants are around 30-35% efficient, which means that maybe 70% of the energy is not captured, which indeed will be released into the environment as heat.
Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
My point is that fossil fuel is a closed cycle - the heat energy is used to sustain life (of trees and humans etc.). The carbon is recaptured in a homostatic manner (over a long period of time, many thousands of years). Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
Whereas nuclear is a permanent release of extra heat energy that is not recovered - eg more uranium and deuterium is not being made by the earth.
Hammersia said:
My point is that fossil fuel is a closed cycle - the heat energy is used to sustain life (of trees and humans etc.). The carbon is recaptured in a homostatic manner (over a long period of time, many thousands of years).
Whereas nuclear is a permanent release of extra heat energy that is not recovered - eg more uranium and deuterium is not being made by the earth.
Coal is formed over millions of years not thousands so as far as humans are concerned it isn't homostaticWhereas nuclear is a permanent release of extra heat energy that is not recovered - eg more uranium and deuterium is not being made by the earth.
Hammersia said:
deckster said:
The energy from the nuclear reaction goes to heat water which drives turbines to generate electricity. Most nuclear power plants are around 30-35% efficient, which means that maybe 70% of the energy is not captured, which indeed will be released into the environment as heat.
Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
My point is that fossil fuel is a closed cycle - the heat energy is used to sustain life (of trees and humans etc.). The carbon is recaptured in a homostatic manner (over a long period of time, many thousands of years). Of course, exactly the same can be said for conventional fossil-fuelled power plants which typically operate at a similar efficiency.
And of course again, practically all energy generated & used by humans eventually ends up as heat, just like everything else. But given that to a first degree of approximation, annual human energy consumption is equal to about an hour of energy that the planet receives from the sun, it's not something we need to be worried about just yet.
Whereas nuclear is a permanent release of extra heat energy that is not recovered - eg more uranium and deuterium is not being made by the earth.
As mentioned above.
The earth is not a closed system thermodynamically. 1.36 (ish) W/m^2 is a metric s
t ton of energy.
Human power generation from nuclear will add to the amount of energy the planet radiates away into space, but if you do the numbers on black box radiation I suspect it’s negligible.
The earth is not a closed system thermodynamically. 1.36 (ish) W/m^2 is a metric s
t ton of energy. Human power generation from nuclear will add to the amount of energy the planet radiates away into space, but if you do the numbers on black box radiation I suspect it’s negligible.
Mr E said:
As mentioned above.
The earth is not a closed system thermodynamically. 1.36 (ish) W/m^2 is a metric st ton of energy.
Human power generation from nuclear will add to the amount of energy the planet radiates away into space, but if you do the numbers on black box radiation I suspect it’s negligible.
Ah, interesting, can you expand on that? That's maybe what I'm wondering, how much heat energy we bleed off into space, how much more energy we bleed off if global temperatures rise? The earth is not a closed system thermodynamically. 1.36 (ish) W/m^2 is a metric s
t ton of energy. Human power generation from nuclear will add to the amount of energy the planet radiates away into space, but if you do the numbers on black box radiation I suspect it’s negligible.
Not at the scale we operate it, or are likely to operate it. Total human energy use per annum from all sources is about 180,000 TWh. That's about as much energy as the Earth receives from the sun in an hour. If we replaced all of our energy consumption with nuclear - all the coal, oil, gas, solar, wind, wood, everything - we would increase the amount of energy arriving on the planet by 0.01%.
Hammersia said:
Ah, interesting, can you expand on that? That's maybe what I'm wondering, how much heat energy we bleed off into space, how much more energy we bleed off if global temperatures rise?
From a pure thermodynamics point of view, in a stable system the answer must be "all of it", otherwise we would be heating up.Of course what we are seeing now is that global temperatures are indeed rising, so the answer, currently, is "not quite enough".
All thermal energy processes will release waste heat, however nuclear differs in that it won't release carbon dioxide as a by-product of the thermal process.
There are some differences between the cooling systems. In a closed system the heat source which will be converted into superheated steam, which passes through a turbine to generate electricity and the steam is cooled down before being recirculated back into the boiler (steam cycle). This cooling can be achieved by air cooling, however in larger scale facilities (coal and nuclear) you're more likely to see wet cooling. This essentially transfers heat from the closed system into a body of water, where the heat is transferred to the atmosphere by evaporation of that water (these are the large cooling towers you see at coal-fired power plants).
The amount of heat released will have virtually no impact on the temperature of the planet. Excess heat from nuclear can be used, for instance in heating networks or desalination, so it's not all lost.
I sit on the fence when it comes to the environmental credentials of nuclear energy; I don't personally view nuclear as a renewable source of energy, however it is 'low carbon'. That is, if you exclude the amount of concrete and other materials required to build the plants. The footprint of the plants is small when considering the vast amounts of energy they produce.
There are some differences between the cooling systems. In a closed system the heat source which will be converted into superheated steam, which passes through a turbine to generate electricity and the steam is cooled down before being recirculated back into the boiler (steam cycle). This cooling can be achieved by air cooling, however in larger scale facilities (coal and nuclear) you're more likely to see wet cooling. This essentially transfers heat from the closed system into a body of water, where the heat is transferred to the atmosphere by evaporation of that water (these are the large cooling towers you see at coal-fired power plants).
The amount of heat released will have virtually no impact on the temperature of the planet. Excess heat from nuclear can be used, for instance in heating networks or desalination, so it's not all lost.
I sit on the fence when it comes to the environmental credentials of nuclear energy; I don't personally view nuclear as a renewable source of energy, however it is 'low carbon'. That is, if you exclude the amount of concrete and other materials required to build the plants. The footprint of the plants is small when considering the vast amounts of energy they produce.
Mr E said:
Over a large timescale everything is renewable.
Over a very significantly large timescale nothing is as the universe proceeds inexorably towards entropy and heat death.
(I agree, low carbon is a better term)
Define 'renewable'. I suggest that it is a resource which is replenished within our lifetime. Then, for sustainable practice, that 'renewable' resource should be replenished at a greater rate than it is consumed. Over a very significantly large timescale nothing is as the universe proceeds inexorably towards entropy and heat death.
(I agree, low carbon is a better term)
Apparently the exact time for a rotation varies quite a bit day to day. Makes sense but I never thought about it until now.
https://www.timeanddate.com/time/earth-rotation.ht...
https://www.timeanddate.com/time/earth-rotation.ht...
Edited by budgie smuggler on Monday 7th August 17:06
Roofless Toothless said:
This OP thinks like me. 
Only my niggle is that wind generation and tidal barrages slow down the earth's speed of rotation. Not by much, but they do - and it is irreversible.
I get the tidal thought, but the mere existence of tides is drag on the earths rotation (and causes the moon to move further out). Eventually the earth/moon will become tidally locked and there will be no tides. I presume any extra energy extracted via tidal power accelerates that?Only my niggle is that wind generation and tidal barrages slow down the earth's speed of rotation. Not by much, but they do - and it is irreversible.
I’m not sure I understand the wind hypothesis. The energy you extract from the wind is the difference between the rotation of the earth and the atmosphere which is driven by sun ultimately - not the KE of the planetary system?
(Edit - this really is a conversation that needs a whiteboard and a number of beers)
Any increase in temperature caused by release of energy is radiated off into space due to the higher temperature differential.
Co2 doesn't work like that, because it absorbs more of the radiation from the sun, trapping it as heat. There might be an argument that the water vapour released might act as a greenhouse gas - I'm not sure.
Co2 doesn't work like that, because it absorbs more of the radiation from the sun, trapping it as heat. There might be an argument that the water vapour released might act as a greenhouse gas - I'm not sure.
LimaDelta said:
You'll have bigger problems than no tides, you'll have a rapidly cooling core when the 'squash ball' effect ceases.
What proportion of core heat is residual from formation, from radioactive decay and from gravitational ‘kneading’?(I genuinely have no idea)
Cold core, tectonics stop and the whole planet dies? Does the sun run out of fuel first?
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