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View Diary: Wind power set to decline under Obama? (270 comments)

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  •  Sounds like you're talking about (0+ / 0-)

    a variant of SEGS.

    •  Well, no ... as far as I can tell ... (1+ / 0-)
      Recommended by:

      ... from Wikipedia (unless you mean SONAR/Environmental Group Simulator), that uses gas directly to compensate for volatility in solar thermal capture ... it does not seem to temporarily store the heat collected to shift generating capacity toward consumption peaks the way that the molten salt systems seem to aim to do.

      But it might indeed be capital efficient to provide for combined cycle natural gas generation by using the exhaust of a peaking gas turbine as a supplementary heat source at a solar power source that was already designed around that kind of temporary heat storage system.

      •  SEGS (0+ / 0-)

        Link.  Doesn't store the heat (heat storage can have very high capital costs), but it does use natural gas to compensate for fluctuations in supply or demand.  And since you already have the turbines, it's no significant extra cost.

        I really like the concept.  Natural gas is already a rather clean, low carbon fuel, and here it's only supplemental.

        •  What I was talking about was stealing the ... (0+ / 0-)

          ... technology.

          Combined cycle gas generators work with a first cycle of gas turbines, and then the second cycle is a steam generator that uses the heat from the exhaust of the turbine. That is much more thermodynamically efficient than turbine alone.

          The thing is, the capital costs are substantially higher, and the higher the capital cost, the more you want to use the capital. On the other hand, peaking gas plants that are gas turbines alone are thermodynamically inefficient. However, if peaking gas plants had their exhaust heat stored in molten salts for second cycle generation, the first cycle could be used in the bursty way that gas turbines are normally used, and the second cycle generation could be spread out over a longer generating period, reducing the capital cost to output.

          But if you had a peaking gas plant that was auxilliary to a concentrated thermal solar power producer, precisely when it is generating is when solar incidence has dropped, so using the gas turbine exhaust as a supplementary heat source for the solar power generator seems like a very natural fit. It would reduce the size of the peaking gas turbine you need to even the load.

          Huh. I didn't know that SEGS had that auxiliary generating capacity, but under common US wholesale power payment regimes, it makes sense.

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