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Wednesday, November 13, 2013

It's Raining Soup

Robert Heinlein wrote in Friday that it was “raining soup”—meaning that we have no shortage of energy. The sun is raining energy for free. All we need is a pot to catch it.

Indeed, the Earth is supplied with an enormous amount of free energy on a continuous basis. And we let almost all of it fall on the ground. But, solar cells are reaching a level of maturity which promises that we will never have an energy problem in the future.

It's well known that there has been a theoretical limit on the amount of sunlight current solar cells can convert into electricity. Called the Shockley–Queisser limit, or SQ for short, each solar cell is limited to converting a maximum of 30% of the solar rays which fall upon it. Currently, the most efficient solar cell has achieved 25% efficiency and a German lab reports near 50% efficiency. New technology which is coming soon will use a cascade of solar cells to raise the limit to 86.8%. Consequently, we should be able to capture most of the “soup” raining down on us by building an efficient “pot” to catch it.

What does the new wave of solar cells mean for our species? First of all, the elimination of fossil fuel burning will happen soon. Earth will continue to warm, but the extinction scenario is gradually becoming less likely. The economics of solar will eventually bankrupt anyone who wishes to continue polluting the environment with the products of fossil fuels. The future is bright.

One thing that we really need now is storage of solar power. Because of the intermittent nature of solar power, we need to store several days worth of power to use at night and on extremely cloudy days. That, too, is under development right now and could burst upon the scene very soon.