Devil's advocate on solar



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Posted by: stak
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Posted on: 2014-10-15 22:17:55

Sometimes I wonder if solar panels really are better than fossil fuels. One the one hand, yay renewable energy. On the other hand, aren't we trying to reflect away more of the sun's energy to avoid amplifying global warming? Solar panels seem to work counter to that goal - they capture more and more of the sun's energy and trap it here.

Arguably that energy ends up mostly dissipated as heat (e.g. in the case of a solar-powered data center), and that would be the same if the data center were powered by fossil fuels. But I can't help thinking of our planet as a mostly-closed system that ordinarily emits about the same amount of energy that it takes in (that may not be right). Solar panels seem like they would upset that balance.

I wonder if anybody has done studies to measure this sort of thing.

Posted by erlogan at 2014-10-15 22:24:41
Ultimately, burning fossil fuel is a release of solar energy, too. It's just been stored in a roundabout fashion. If you want to continue the metaphor, better to keep it sequestered.

The planet isn't a closed system. Without a constant stream of incoming solar energy, we'd freeze and die pretty fast.
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Posted by stak at 2014-10-16 08:31:08
Hm, true. I wonder why I think of it as a closed system...
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Posted by varun at 2014-10-16 22:09:41
I think the other aspect of global warming is that we're trying to reduce the emissions of greenhouse gases, particularly CO2 and CH4, which are extremely potent "trappers" of energy. So while we could reflect a portion of the sun's energy away (ice caps, white roofs and roads, mirrors, solar sails), it's much more effective to stop the energy cycle from running away under greenhouse conditions.

Besides, the sun is going to be shining that 235W/m2 onto the planet regardless of whether it's being harvested or not. You might as well use it, and reduce the use of other energy sources. Eventually, you might reach a point where we're meeting all our energy needs from solar - at which point of time, it will indeed make sense to reflect the rest into space to counteract centuries of anthropogenic forcing.

FWIW, I think part of the solution in Greenland is to use solar-powered pumps to spray part of the melt back onto land. Given a small enough particle size, it'll freeze before it hits the ground, and you've just taken that out of the ocean. Run it for six months of the year 24/7 on solar and you'll literally start making a dent in the ocean in a couple of years. I've not run the numbers recently, but I can if you want.
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