Sunday, June 1, 2008

Solar thermal is different


Solar thermal is able to very efficiently store energy in the form of a fusible salt. During the day, the salt is melted using the excess heat not being used to generate power. At night the melted salt re-solidifies releasing heat. Wind power generation has no such convenient energy storage mechanism.

Furthermore, given that solar thermal is a heat source, once you get to the actual power generation stage it is basically the same as a conventional nuclear or coal plant (which are simply heat sources as well). A steam fired turbine is run by the heat source using the Rankine cycle and connected to the electrical grid in the conventional manner. That also means there is a throttle where the operator can control just how much energy is put into the grid and how much is added to / removed from storage. For wind you literally are at the mercy of the wind.

Plus we can accurately predict when the sun will rise and set. The wind? Not so much. Like all solar sources, they are best located in a location where the sun mostly shines during the day (duh). Even so, because of their efficient energy storage, solar thermal can be much more easily set up to continue to generate power during cloudy days.

For those reasons, and numerous others, wind power, compared to solar thermal, is much more difficult to use effectively.

You need to call up and berate Teddy Kennedy who is opposing windmills off the coast of Cape Cod because they might interfere with sailing his yacht. The locals in Carteret county are fighting like hell to prevent the installation of windmills as well. People in the Blue Ridge Mountains ("green" groups in particular) who worry about "the viewscape" are fighting like hell to prevent installation there.

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