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Free energy from the sun

Photovoltaic cells which convert sunshine directly into electricity have a place in the country’s mix of energy sources.  One of the best features of solar power is that it peaks just about the time summertime loads are greatest.  This helps offset solar’s high construction cost and comparatively low productivity because wholesale electric prices at peak demand times can be ten or even a hundred times the typical rate.  Solar is most productive when prices are highest, which is good for everybody.

Installed solar cell costs are coming down, but they’re still pretty high.  A typical power plant of  “utility” size is around 800 megawatts, or to put this in round numbers and familiar terms, about a million horsepower.  A typical coal-fired plant of this size might cost, say, $3 to $4 billion to construct.  Online sources say solar construction using the best thin-film arrays could produce a million horsepower of electricity for slightly more than the cost of a coal plant.  And that’s not bad, not bad at all, because fuel costs are zero, and maintenance costs are reduced, and so on.  Solar is starting to look a little bit competitive.

The problem, of course, is that a solar plant produces nothing in the dark, and utility customers are really fussy about wanting their power on at all hours of the night.

So, what to do?  Well, you still need to have a whole fleet of big, million-horsepower sized power plants to run the lights, factories, subways, and shopping malls when the sun goes down.  So all those installed costs still have to be maintained along with all the support staff and engineering structures such as railroads to deliver the coal.  The problem of nighttime power demand will intensify once electric cars become a significant factor in transportation, because people will charge their batteries when they get home at night after all the work and shopping and kid-taxi services are done.

The best use of solar power, then, is to help supply peaking loads on hot summer days when loads are maxed out.  This is true regardless of whether the solar sources are consolidated into massive sun farms or distributed across rooftops everywhere.  This makes economic sense.

What makes no sense is any claim that solar could, for the foreseeable future, displace a significant fraction of coal, gas, nuclear, and hydro power as a source of baseload energy for America’s huge electric needs.  Someday, new technologies for energy storage may be developed which will help solar’s little darkness problem.  But until that day arrives, solar is simply not economically capable of being any more than a peaking  source, a niche in the energy mix.

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  1. A View from the Altar on 05-Jun-09 at 19:20 pm

    […] percent return.  That’s not bad, which is why I’ve written previously that solar power should have a niche role to play in America’s energy future.  Solar voltaics don’t show as much promise, I […]

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