Yet you said it was only 20% efficient. Where did the 80% of the energy go?
> it requires 3-5x MORE ENERGY to impart the THE SAME AMOUNT OF HEAT to a rock as it does water
No, it doesn't. It's the same. Unless you've confused heat with temperature. Or you didn't try to heat the rock in an enclosed, insulated box, and the rocks were radiating the heat away almost as fast as it was applied.
"Heat is a form of energy that can be transferred from one object to another or even created at the expense of the loss of other forms of energy."
https://www.physicsclassroom.com/Class/thermalP/u18l1d.cfm
QED.
> No, it doesn't. It's the same.
This statement is the entire premise of your argument, but is directly refuted by the source you provided, and is so ridiculously absurd that I can't take you seriously anymore. You have to be trolling.
Then it should be no trouble for you to present a literal quote of what I said and a literal quote that says the opposite.
Your gaslighting continues, and I'm beyond tired of it.
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.
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.
As I've explained multiple times now, it's a matter of where the heat originally came from, and it requires 3-5x MORE ENERGY to impart the THE SAME AMOUNT OF HEAT to a rock as it does water. That's the entire point, and is the portion of thermodynamics that you keep pretending doesn't exist. I'm not sure how many more times or ways I can explain this to you, because you clearly don't want to accept that the original heat input doesn't magically manifest itself.
I've provided you with evidence for all of this, but you're still making the same baseless argument. Your ignorance of the subject is exhausting to engage with, so if that was your intent, I guess you win today's Troll Award. But you're still completely wrong about the science, you're unwilling to provide any evidence to back up your claims (because the evidence doesn't exist), you have no basis for your argument at all, and you should be ashamed of yourself for insisting otherwise in such an aggressively arrogant manner.