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So these orbital power stations would be in high orbit, capturing sunlight 24/7, and transmitting it to Earth via microwave radiation. That's energy (and heat)

So these orbital power stations would be in high orbit, capturing sunlight 24/7, and transmitting it to Earth via microwave radiation. That's energy (and heat) that would otherwise have passed by Earth, now entering Earth's biosphere. What would that do to the climate?

GenerocUsername 4y ago
I'm fairly certain current global warming concerns are not caused by heat generation but by heat retention. And we do generate a lot of heat via fossil fuels. So generating additional heat (adding heat to the system) is not a current or future concern as long as heat retention stops growing
- lven 4y ago
  Doesn't matter if the heat is coming from burning more fossils or nuclear fuels or intercepting more solar light - the effect on Earth's temeperature is negligible for now. You can do simple heat balance with Stefan Boltzman Law to show that the temperature of the Earth would increase by less than a tenth of a degree even if we burned 10x more fossil or nuclear fuels. The idea is that all the energy received and and generated on Earth must be reraridated at the Earth's blackbody temperature, and it only changes as the power to the 1/4th - so very small compared to the absolute temperature of the Earth ~300K, and the changes (e.g. seasons).
picsao 4y ago
jbotz 4y ago
Well, first off this energy would be initially replacing energy that was previously coming from fossil fuels, so on account of that not much. But, as Stross points out there is a 70% loss in transmission, and presumably most of that ends up as heat in the atmosphere. Now as to the question of how significant is the waste heat from that energy? I once did a ball-park calculation in which I determined that something like 4% of global heating comes not from greenhouse effect but from waste heat[1]. If that's right, then if we replace all of our energy usage with space-based solar of which only 1/3 makes it to earth and the rest is turned to waste heat we'd be be down to about 12% of current (combined green-house and waste heat) global heating. That's seems like a huge win, and we'd have enough energy to spare to start extracting CO2 from the atmosphere until we even compensate for that. [1] I can't find my calculations right now, and I'd love for someone to independently check that.
- justsomehnguy 4y ago
  > that something like 4% of global heating comes not from greenhouse effect but from waste heat Amount is a subjet of the methodology, but to understand that there is a significant amount of, essentially, heating up of the street someone doesn't even need a fancy IR camera.

GenerocUsername 4y ago

I'm fairly certain current global warming concerns are not caused by heat generation but by heat retention. And we do generate a lot of heat via fossil fuels. So generating additional heat (adding heat to the system) is not a current or future concern as long as heat retention stops growing

lven 4y ago
Doesn't matter if the heat is coming from burning more fossils or nuclear fuels or intercepting more solar light - the effect on Earth's temeperature is negligible for now. You can do simple heat balance with Stefan Boltzman Law to show that the temperature of the Earth would increase by less than a tenth of a degree even if we burned 10x more fossil or nuclear fuels. The idea is that all the energy received and and generated on Earth must be reraridated at the Earth's blackbody temperature, and it only changes as the power to the 1/4th - so very small compared to the absolute temperature of the Earth ~300K, and the changes (e.g. seasons).

picsao 4y ago

jbotz 4y ago

Well, first off this energy would be initially replacing energy that was previously coming from fossil fuels, so on account of that not much. But, as Stross points out there is a 70% loss in transmission, and presumably most of that ends up as heat in the atmosphere. Now as to the question of how significant is the waste heat from that energy? I once did a ball-park calculation in which I determined that something like 4% of global heating comes not from greenhouse effect but from waste heat[1]. If that's right, then if we replace all of our energy usage with space-based solar of which only 1/3 makes it to earth and the rest is turned to waste heat we'd be be down to about 12% of current (combined green-house and waste heat) global heating. That's seems like a huge win, and we'd have enough energy to spare to start extracting CO2 from the atmosphere until we even compensate for that. [1] I can't find my calculations right now, and I'd love for someone to independently check that.

justsomehnguy 4y ago
> that something like 4% of global heating comes not from greenhouse effect but from waste heat Amount is a subjet of the methodology, but to understand that there is a significant amount of, essentially, heating up of the street someone doesn't even need a fancy IR camera.