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View Diary: Why wind needs feed-in tariffs (and why it is not the enemy of nuclear) (161 comments)

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  •  Doesn't have to be water... (2+ / 0-)
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    NRG Guy, Stranded Wind

    Back in the 1980's, they built a prototype plant in Arizona:

    They used molten salts as a working fluid.

    In a molten-salt power tower, the molten nitrate salt,Molten_salt_system which is a clear liquid with properties like water at temperatures above its 240oC (464oF) melting point, is pumped from a large storage tank to the receiver, where it is heated in tubes to temperatures of 565oC (1049oF). The salt is then returned to a second large storage tank, where it remains until needed by the utility for power generation. At that time, the salt is pumped through a steam generator to produce the steam to power a conventional, high-efficiency steam turbine to produce electricity. The salt at 285oC (545oF) then returns to the first storage tank to be used in the cycle again.

    As for what they used in the Spanish plant, I don't recall.  I think it was a much smaller amount of storage, that would only be suitable to cover a reduction in sunlight due to a passing cloud or some such, but it is ultimately a cost/benefit decision and not a technical issue.

    As for efficiency, I don't recall reading any numbers, and it can be somewhat misleading to simply compare the amount of solar that lands on the land on which the plant is built.  Perhaps a better comparison is to compare the amount of solar energy that is collected by the mirrors to the amount of electrical output.

    More info here.  There are several types of designs out there, and at this point the industry is still young enough that they still haven't standardized everything yet.

    •  One other point to mention... (1+ / 0-)
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      Stranded Wind

      There are those that have very ambitious plans for CSP:

      that essentially involve CSP plants in North Africa, and high voltage DC lines to bring the power up into Europe.

      At the link above, there is a Google Earth kmz file that you can download.  Most CSP plants are large enough that they can easily be seen from Google Earth, and it is kind of fun to look them over.  Some of them are new enough that they don't appear on the photos.  In some cases, someone has made the effort to figure out the real location, in other cases the locations are just approximate.

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