| > What is the round trip loss from heating up rocks and getting the energy back? It is huge. And you artfully forgot to mention all the equipment needed to get the energy back out in usable form such as electricity. If you store the energy by heating the rocks, you can recover it to heat your house by simply blowing air over the rocks. No need to convert it to electricity, which would indeed be silly. The same goes for air conditioning. Excess electricity could be used to cool the rocks, which then can be used to cool your house when electricity is expensive. The detour through the rocks (or anything with thermal mass) costs next to nothing. I am not talking about using the EV battery to run the house. I am talking about using the EV battery to run the EV. Simply charge it when electricity rates are cheaper. It's shifting the demand. > thinking that they constitute a solution They are perfectly and cheaply implementable, and are part of the solution. > half-assed I actually have a degree in mechanical engineering. You shouldn't be so hasty in your inferences. |