Monday, July 29, 2013

Solar project uses 120,000 metric tons of molten salt

 We were surprised at first to read that the giant Abengoa Solana solar energy project had to import 120,000 metric tons of molten salt from Chile.  After all, Arizona has numerous massive salt deposits some of which are being actively mined.   But then we learned that the molten salt mixes for thermal storage are typically 60% sodium nitrate and 40% potassium nitrate.   The mixtures vary and and also include calcium nitrates.

The 280-megawatt, 3 square mile, $2 billion project will use the molten salt as a heat storage sink that will allow electricity to be generated for as long as 6 hours after the sun sets, according to a report in the Arizona [Phoenix] Republic.   [Right, diagram of plant design.  Credit, US Dept. Energy]


  1. John Moore8:45 PM

    Isn't that mixture explosive? I hope we don't have a .12 kt explosion out in the desert some place.

    1. This question has been asked before and the response is that this mixture is not explosive.

      For an industry sourced FAQ see:

      Perhaps you're reminded that when potassium nitrate is mixed with black carbon powder and sulfur it makes gunpowder.

    2. Anonymous9:54 AM

      True, the potassium nitrate is stable on its own. You can buy it at the local feed store, it is used as a fertilizer.

  2. Anonymous7:35 PM

    Can anyone help me figure out energy required to raise the temperature of the mixture of 60% sodium nitrate and 40% potassium nitrate in liquid state buy one degree. Thanks