Friday, March 07, 2008


Following up on my last post on solar electric. One idea that has been around since the 1970's is the solar-thermal concept. This uses sunlight focused by mirrors to heat water and run a steam turbine. Even though it sounds a bit Rube Goldberg-esk compared to the direct conversion of sunlight into electricity, it actually is more efficient. It also would tie better into the grid by generating true alternating current rather than the pseudo-AC that inverters produce (solar electric panels can only generate DC). A demonstration plant was supposed to be built here in Arizona, but of course never got off the ground.

A company called Ausra claims to have a solar-thermal technology that can provide 90% of the electricity used by the United States using "only" 9,600 square miles (Vermont) provided that someone, somehow, somewhere can develop "the ability to store energy for 16 hours, thus creating a stable power source through cloudy periods and the night, a feat that has so far eluded engineers." That's sort of like claiming that you have a vehicle that can get 1,000 mpg as soon as someone develops an engine that gets 1,000 mpg. Energy storage for nights and cloudy days has always been the stopping point of any solar energy concept. The rest is old hat that we have known how to do for decades.

There are answers, of course. The bulk of electricity is used during the daytime. Use solar energy technology during the day and nuclear at night. Or put the solar panels in space where the sun never sets and the "sky" is never cloudy, and beam the energy down.

Or just do what we are best at doing: nothing.

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