At 8:42 AM 4/9/5, Robin van Spaandonk wrote: >At several times the energy density of lead-acid batteries, and a >fraction of one percent of the cost, a possibly very cheap form of >temporary energy storage, especially on a large scale, is molten >salt. At the temperature difference between molten NaCl (800 ºC), >and room temperature, the Carnot efficiency is quite high (72%), >and Sterling engines could be used to retrieve the energy stored. > >The only potential problem is the chemical aggressiveness of the >molten salt, but I'm sure that could be overcome.
Storage of *both* the heat and cold generated by air liquifaction might be a sensible way to go. Liquid air is easy to store at high efficiency, and heat from compression can be stored in thermal wells or by using salt phase exchange, though a much lower melting point salt would have to be used to directly obtain the heat from the compression. I would expect thermal wells to be cheaper than salt tanks, and if drilled deep enough, they produce geothermal heat also. Regards, Horace Heffner
