Brian, buddy, as just an outsider reading this thread I want let you know that Walter is right and you are coming across as rather confused. Also, your aggressive stance isn’t helping.

Walter is right about what, exactly? That heat can be transferred between objects? That heat can be released from objects? Nobody ever refuted those, and those are the only points he has made so far in defense of rocks being a be-all end-all solution which, again, doesn't factor in any of the actual physics involved which make it inefficient.

If you need evidence of that, feel free to read any of the provided materials, especially the concrete heat storage systems that have already been built which, unsurprisingly, use 2x as much electricity to store 50% as much heat.

So, unless you have actual information to provide, you saying I'm wrong doesn't add anything to the conversation.

If it takes X amount of energy to heat a material by Z degrees, then presumably the material radiates exactly X amount of energy back out when it cools down by the same Z degrees, no?

What does it matter that Y kg of rocks stores that energy at a lower temperature than Y kg of water? Or, conversely, that if you insist on having your energy-storage temperature set at some specific Z' degrees, you can store that amount of heat energy in much fewer kg of rocks than of water?

You're mixing up temperature and energy. They're not the same thing.