Sunday, July 31, 2005

eco: solar progress uphill

Harnessing solar energy economically is the great engineering challenge of our time. My partner and I are putting solar thermal and photovoltaic on our new house, but we'll spend US$ tens of thousands of dollars (after tax breaks) just to save $100 a month in in electric and heating bills. It's an emotional and spiritual decision, not a rational economic one. But if someone can drive the cost per watt or BTU so low that putting in solar becomes an easy way to Make Money Fast, the market will take over.

Energy Innovations, founded by Idealab dot-com incubator guy Bill Gross, has thought so hard about this, it's inspiring.
  • They're focused on a great mission: "Our immediate goal is to reduce the payback time for a solar system so that it becomes a sensible and logical investment to electricity users around the world."
  • They're focused on a great market: the billions of square feet of roofs of commercial buildings that just lie there, unused, baking in the sun.
  • They're focused on cost over technology. Read their entire Innovations section, especially the "Lessons Learned". They looked at Stirling cycle engines, servo-controlled "petal" mirrors, big heliostat arrays, Fresnel lens concentrators, ... and abandoned them because they couldn't get them cheap enough in a short timeframe.
Yet even with all that focus, it is still so damn hard. Solar cells with reasonable efficiency cost money, so you concentrate sunlight on them with cheap mirrors, but then you have to track the sun with a mechanism that costs money. The more you concentrate, the more you can spend on exotic solar cells, but then you have more mechanical engineering. And the concentrated sunlight bakes the solar cells: you could try to capture that thermal energy but that raises cost and compexity, so you have to come up with a cooling system. The tradeoffs are everywhere.

There are other companies with big ideas: cheap PV films, PV coatings, nano-scale concentrators, etc. While these efforts that could change the fate of the Earth get a few millions in venture funding, the 2005 US energy bill gives around $6 billion dollars in tax breaks to carbon-spewing global-warming smog-creating oil, ethanol, and coal producers.

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