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Solar energy after the sun sets

I am a new member but I did not see this idea proposed yet. Using a highly efficient air compressor to compress ambient air which also compresses the solar heat which is in turn used to heat a sterling engine. The sterling engine turns the compressor (initially this process will need a jump start) and then the compressed air is used to spin an electric generator. But because the heat has been removed from the compresses air it is used to absorb heat from the other side of the sterling engine thus improving its efficiency. The output would be free electricity and water that fell out of the air when compressed. The energy that powers this process is pure solar so nothing magic is going on. Any thoughts?


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    Mar 19 2013: I don't think a sterling engine will be powerful enough but compressed air has been used as a mass storage of energy before. Typically they use a large geological formation as a tank to store the air. I believe the example I read was a coal powered electrical plant that wanted to run at peak efficiency. Instead of lowering its power during low load time it would compress the air the old unused underground coal mine and then use that air to drive generators at peak load. Other examples use salt domes as a storage tank.

    The loss of power comes from the fact that compressing gases causes them to heat up which can dissipate as an energy loss. Also, when gases decompress they get cold and this can cause mechanical problems with the turbines that drive the generators. To deal with this systems have been designed to use heat exchangers to capture and store some of the heat to reintroduce into the compressed air when it is released. Of course, there is always energy loss. As I understand, these systems are less efficient, but cheaper than batteries.

    If you want to do some research into what has been done in this area, Wikipedia is a good place to start.

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