Walter, you are making up science in your head that does not actually exist. I would highly encourage you to do some actual research before you continue to make these incredibly uninformed comments.
> Because it takes 3-5x as much energy to heat rock than water
And 100% of that energy gets recovered as it slowly returns to ambient temperature.
You're confusing heat with temperature.
> you are making up science in your head that does not actually exist
You should be careful about making such statements. You're quite wrong. The heat going into the rock will be 100% returned. All of it. Where do you imagine it will go?
No, Walter, you're confusing energy with temperature. If it takes 1 kWh of electricity to increase the temperature of water by 1 unit (thereby releasing 1 unit of heat to the atmosphere), it takes 3-5 kWh of electricity to increase the temperature of a rock by 1 unit. That's called inefficiency.
I'm done trying to explain 6th grade Earth science to you. You're either trolling or extremely unwilling to accept reality, so unless you have actual evidence for any of your claims, please stop pretending that you're some super genius who knows better than every scientist and engineer on the planet.
The energy comes back out of the rocks in the form of heat. 100% of it. No losses. Energy in equals energy out. If you heat the rock by 1 degree, in cooling off 1 degree it will release 100% of the heat absorbed.
> you're some super genius who knows better than every scientist and engineer on the planet
I suggest you ask an actual thermodynamicist, not a 6th grader. I don't need to present evidence that conservation of energy applies. After all, it's the law.
This is getting beyond ridiculous, Walter, and you're making things up again. At no point did I or anyone else on the planet ever suggest that heating a rock by 1 degree will release less than 1 degree of heat.
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.
> At no point did I or anyone else on the planet ever suggest that heating a rock by 1 degree will release less than 1 degree of heat.
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."
You finally provided some "evidence" and it literally says the opposite of what you're suggesting. I would highly encourage you to keep reading the subsequent pages on that site, because it goes on to explain the reasons why you're wrong.
> 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.
Walter, I've already provided you with a mountain of evidence. You pasted a single sentence stating that heat can be transferred between objects, which nobody has ever refuted, and does not factor in any of the actual physics involved with that transfer -- and then you asked me to paste an entire article as a counterpoint.
Your gaslighting continues, and I'm beyond tired of it.
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.
https://news.ycombinator.com/item?id=29186001