Ok, so this makes a lot of sense for renewable sources of energy like wind and solar - production facilities that are distant from bodies of water can store sur

Ok, so this makes a lot of sense for renewable sources of energy like wind and solar - production facilities that are distant from bodies of water can store surplus energy during peak production times (windy or sunny days) and then use that stored surplus when production is stagnant (calm days or at night). The current practice is to use surplus energy to pump water into a reservoir during peak production, and then converting it to hydro-electric power later when production is stagnant. The Isentropic advantage is that you don't need a reservoir to store the energy, the storage system can be build regardless of geography. I have two questions: 1. What kind of insulation does it take to keep the gravel hot or cold enough to store the energy for a long time? Is the energy lost due to natural thermodynamic processes comparable to energy lost due to evaporation in a pumped-hydro storage system? 2. If the storage system is geographically independent, could it be moved in an energy efficient manner? The problem with almost every energy source we have right now is that it has to be close to the population it serves. On the other hand, if we could generate everyone's electricy as solar energy in Nevada or nuclear energy hundreds of miles from populations, and then move it to distribution plants, then we could answer a lot of energy questions.