133: Sand Batteries and Thermal Energy Storage

Hey, everybody on today’s episode of still to be determined, we’re gonna be talking about building hot sand castles. That’s right. We’re talking about Matt’s most recent episode, how a sand battery could change the energy game. This episode was on August 30th, 2002 as usual. I’m Sean Ferrell. I’m Matt’s older brother.

I’m a writer. I write some sci-fi. I write some stuff for kids. and I’m always curious about new technologies or in this case, just a new use of a hot beach. I mean, that’s, , that’s effectively what we’re talking about. There’s nothing. Oh, God hot, hot, hot, hot, yeah. Running across the sand. Like this battery is so hot and of course you can hear him there in the background, Chortling along.

It’s my brother, Matt. And he, of course, is the Matt from undecided with Matt Ferrell, Matt, how you doing?

I’m doing well. How about you? How’s the weekend

I’m doing okay. It’s been a beautiful weekend here in New York city. It’s of course this is labor day weekend. So the unofficial end of summer and the city certainly feels like it.

People are out of the city or out in the city trying to enjoy it. And thankfully, we’ve had some nice weather this weekend, so it’s been a lot of fun. How about yourself? You enjoying it? Just

taking a lot of time off and just trying to relax this weekend. It’s been really nice.

So do you actually have a summer where you like back off the work a little bit, because not this year, I don’t see a break in your videos, so no it’s been nonstop.

Well, that’s good for all your listeners and viewers. That’s. That’s what they prefer.

I’m sure I’m sacrificing my vacation for everybody.

that’s right. And we continue to hear back from all of you. We appreciate your feedback. Of course, it helps drive both Matt’s program where some of his topics come from his viewers and conversations he has with his community.

And right here, the entire point of this is an after show discussion. So. I like to share some comments from previous episodes of still to be determined like this one from Daniel Boger, who was responding to our conversation on phase change materials. These were the energy absorption materials where they changed from state to state and recapturing the energy.

Going from state to state effectively makes them like batteries. And Daniel wrote, I didn’t make the connection until you were talking about how common phase change materials are for space, but in AIS, by Andy Weir, he goes into why heat rejection is a change on the moon. It ends up being a big plot point, but one way the characters deal with it is wax.

They let the excess heat melt a tank of wax, then cool. The wax back to solid later. So yeah, this is something. Hard sci-fi has been playing with for a long time. So this is not a new concept. It’s a new application as you talked about it, but it’s not a new concept. And then right after Daniel’s comment was this one from Richard Mariano who wrote, I’ve been looking for a low-cost way to heat my compost piles.

Since my yard doesn’t get much sun PCM gave me the idea of building myself a Perin based heating box, charging it. Every time I cook by capturing the ambient heat from my. Huh, and I was just dumbfounded by why you got some big brains watching your channel. This is, yes. This probably

smart people watching my videos.

I mean, this is

like classic engineering approach to my son. The sun doesn’t hit my yard enough, but I’ve got all this heat in my kitchen. How do I move it? And it’s effectively by using parafin it follows on Daniel’s comment. Perfectly. Yeah. Fiction on my science compos. There’s wax everywhere. So on

my discord server, somebody was commenting about how they recapture the heat from the refrigerator.

So like, you know, behind the refrigerator is pretty hot. Yeah. Like there’s a lot of heat cuz it’s, it’s a heat pump, moving the heat from inside the fridge outside. And so they’re taking that heat and they’re capturing it and they’re reusing it for something else in their home. And when they were talking about how they were doing this, it was like, like mind blown.

The ingenuity of some people is, is fascinating. I love it.

So today’s discussion is going to follow in these footsteps. It’s how a sand battery could change the energy game. And this is effectively, I mean, effectively, just a giant tank filled with a material and a heating coil and the heating coil super heats the material inside, which in the case of what you were talking about is sand, but it seems clear that it doesn’t have to be sand.

It can be any material that will retain heat. And then because of the insulation of the tank, It holds this for an extended period of time and then could be released. You make the point in your video. It could be released to turn turbines, to generate other forms of energy. Correct. The most direct use just as heat could be the most efficient.

So right. Using this for heating on a large scale of district. Heating methods. It seems like how simple could it be? How could it possibly work? Like hot sand driving heat to heat homes in a neighborhood.

Yeah, this is, this is one of those things of like a, you’re almost a face Palm. Well, well, duh, why aren’t, why, why aren’t we doing this already?

This seems so simple. And, and the, one of the reason that like thermal energy storage systems like this don’t necessarily make sense for converting back to electricity is steam turbines are typically only about 40%. Efficient for converting that heat into electricity. So there’s a lot of energy loss, uh, that you’re not, you’re not capturing and taking advantage of.

So if you’re talking about a boiler system, it’s just heat to heat, it’s like you’re getting a much better efficiency of just moving a heat around to reuse it. It’s a smarter way to, to reuse this. And I do wanna point out that I didn’t go into in depth I kept it very high level for how the gigantic Thermo of sand actually works, but they have this kind of like proprietary system of the way that they have the, the tubing patterned inside the sand and the way it’s so efficient at with holding that heat is they’re not heating the sand, like the tubes.

Aren’t the steel tubes inside. Aren’t going right to the edge. So they’re almost using kind of like the outer perimeter of sand as part of the insulation within the unit itself. Right. And then you have like a double layered steel silo that has insulation inside it. So it’s, it’s just a very clever, simple way that they’ve kind of engineered this gigantic Thermo to hold the heat as efficiently and as long as they possibly can until it’s needed.

Right. It’s, it’s a very clever system. Is

the silo itself. Kind of vacuum seal. Is there? Yeah. Like, because I, the only thing I could equate this to, and you mentioned Thermo, I have a travel mug that has a vacuum seal between the inner chamber and the outer wall mm-hmm and it keeps like I’ll put a beverage in there, hot coffee in the morning.

Yeah. And that coffee has retained its heat. For a better part of the day. It’s remarkable. I’ll forget about it. And then I’ll pick it up and it, and the coffee inside will still be hot. How is the heat not dissipating from this silo system? Is it just because it’s a double chamber?

That’s like, I didn’t have a chance to talk to them directly about this, but I have read about how it works and seen other reports of how it works.

And it’s kind of complicated. It is losing heat over time. It is gradually losing heat. That’s it’s just inevitable. But it’s the combination of that double walled system with the insulation in between them as well as a certain portion of the sand is not like directly heated by the pipes. So the sand itself is kind of helping to.

Hold prevent the heat

from

escaping to the wall. Right? So the, the combination of all this together is helping to keep that heat retained as long as, as they possibly can in a cost efficient, cheap, simple way of manufacturing it, which is kind of the secret sauce, cuz it’s, it’s not just, oh, we can store heat.

And it’s it’s how can you do it? Affordably cheaply and like roll this out really quickly. So they’ve engineered a system that’s kind of drop dead simple. Yeah. So it’s very cost effective and they’re very doing some clever just engineering work to figure out the best way to do it.

It’s really interesting cuz it kind of helps illustrate.

We talked about this similarly last week in how there are some principles of in, in physics. Mm. That escape, our ability to comprehend because the visibility of it, the sensation of it doesn’t match with what’s actually happening. So we have this interpretation that seems to miss these things, and it feels like this system is really highlighting.

If I held up a battery to our audience and I said, this will hold electronic electricity for years, our audience would say, yes, it’s a battery. Mm-hmm . And then if you point at the silo and say, this is also holding energy for an extended period of time, but it’s heat heat, somehow doesn’t seem to be in the same zone.

Yeah. As electricity, it would like. Yeah. How is that? Even what no. That doesn’t make sense. I can’t, I can’t wrap my head around because we’re accustomed to, oh, it’s hot in here. You open the window. It cools down. Heat is something that comes and goes. Heat is something that rises and falls in the room. I cool the room with an air conditioner.

I don’t think in terms of like that heat has gone somewhere for me, it’s just disappeared. The reality being what the air conditioner is doing is taking the heat and sucking it. Moving outside. Yeah, exactly. It’s, it’s a difficult thing to really it’s counterintuitive. Yeah. Is very counterintuitive, counterintuitive.

And the idea that it’s, you keep going back to this in your videos recently of referring to them as batteries and

part of me they’re technically not, they’re technically not batteries. There were many, but the

idea of energy storage, a battery as energy storage, it kind of like, I keep tripping over that, like, oh yeah, this is a.

That just because I don’t feel it on my skin anymore. Doesn’t mean it’s destroyed or dissipated. It means it’s moved. Maybe it’s moved by evening out across an entire room. You have a hot oven, you open up the oven door, you feel the heat move out and then it eventually fills the room and then eventually it dissipates completely.

And it’s no longer hot, but that doesn’t mean that that heat is destroyed.

You’re talking about the conservation of energy. That’s the basic principle we’re talking about. And I remember learning about it in like junior high, high school, you know, learning about conservation of energy. And I remember as a kid going, yeah.

Yeah. Okay. That’s interesting Uhhuh. Oh, that’s kind of neat. And then just like completely forgetting about it for years. And as I’ve been getting back into this, it’s kind of like, oh, oh, conservation of energy in effect. Here’s a great example of it. So it’s yeah. It’s one of those I agree with you completely counterintuitive.

And I. Don’t, I’m not calling on any specific comments, but there were a bunch of comments of people saying this is not a battery. Technically a battery is two chemicals, creating a reaction it’s chemical batteries of battery. Right, right. And they’re not wrong. I’m absolutely correct. Uh, that’s the technical definition of battery.

But the part of the reason I keep using the word battery, when I talk about these things at a high level, to get people quickly to wrap their head around it is to get people to quickly wrap their head around it. Right. Because what you’re talking about, it’s like, It’s energy storage. It’s thermal energy storage.

Yeah. But if you basically say to people, it’s essentially a heat battery, it’s like people then can, can go.

Oh, oh, okay. Yeah. It’s more of metaphor as opposed to it’s a metaphor.

Yes. It’s not literal.

It’s a metaphor. So I wanted to share this comment from little Wolf, 2000. Wolf rights. I’m curious if this could be scaled down to be used for residential batteries slash heat storage and for off grid systems, you could probably remove the inefficiencies of the converting power by using lenses to super heat air during the day and use it to heat the house during the night.

I’m curious what kind of insulation and size would be needed to store enough mass to make a difference? I think that that’s kind of the unspoken in your video is that. Is driven by economies of scale effectively. Yeah. The size of this thing is what allows it to retain the heat. And if you were trying to use this for a single home, it seems to me like you might effectively need something still on the scale of.

The massive one in order to have any impact on what you could do with it over a period of time. Yeah.

The size that you’d probably need would probably be bigger than you’d want to use at your house. But, um, I can’t remember off the top of my head. I did put a comment in there in the YouTube channel somewhere.

There is another YouTube channel that did a, he’s a kind of a DIY engineer. Um, he’s British and he did a great couple of videos about this exact thing of how efficient actually is this. And he basically built a little, it’s like a little tank that was like, , mm-hmm, maybe 10 pounds of sand or something in it.

And he didn’t experiment with heating it up and then timing how long it held it and how much, uh, how many kilowatts of heat were still in there after so many hours. And he did the calculations and he was blown away by what he found. Yeah. It’s he was dubious about how well it would work. And he, what he came out with at the end was like, wow, this really is kind of a cool, like no pun intended, a cool, like, uh, technology.

And it’s so simple. Yeah. And he did it himself and his house, like as an experiment, the, the size of thing he built would get him next to nothing course of a day or a week. But he showed that it can be done at any scale that it does. It works. And it’s, it’s a fascinating video to watch how he breaks it down and how he experiments.

I’ll see if I can find that and put into the description on this video, but I did comment about it on the YouTube

video. Yeah. And I’m reminded of the comments that I shared at the top of the episode, which were from the previous episode about phase change. This effectively is doing the same thing as the phase change.

It’s just not changing phases. It’s. Retaining the heat in the material. It’s not changing what the materials situation currently is. It’s not going from solid to liquid or liquid to gas, but it’s doing the same thing. And I’m also reminded, as you were talking years ago, I became very interested in room heating methods using tea candles and terracotta pots.

And there is. Suggested method of using its I forget how many terracotta pots it is, but it’s a couple of different sizes and you put one effectively as a bell over another one. And then underneath you have tee lights, tee candles. And when you burn those, it’s doing the same thing. It is trapping the heat so that as you burn a candle, you’ve got a good amount.

Of heat dissipating very quickly and it just dissipates into the room. But what this does is it traps that heat in the terracotta pots. And the theory is that the motion of the air as the candles burning off oxygen, and it’s having to draw more air in to get more oxygen that is helping to create a cycle where the heat remains within the terracotta pot shells.

And. when the candle is burnt out, the terracotta pots have retained so much heat that they are now warm and they continue to release the heat over a period of time. So it’s big scale is this thing you’re talking about small scale. Yeah. If people are looking for those, like that question from little Wolf, it might not be this kind of sand thing, but there might be other things you can do in your home that are also one of the things that the people, if you’ve look for these on YouTube, you can find.

They always point out, like it’s kind of decorative, you’ve got this kind of like candle glow coming out from underneath the edges of these terracotta pots. So it’s kind of like little bit decorative and you put it on table in the back of the room. Obviously that’s not something that I would call passive.

You wouldn’t wanna light these and then go to bed. But, um, it’s an interesting utilization of, of again, slow storage of heat over time to allow slow release of heat over. Yep. There was also this comment from James Niern that I thought was like, kind of like hitting multiple birds with one stone using unrecyclable brown or green glass powdered for the sand would also create a use for the material instead of sending it to landfills, using glass, instead of sand would also keep the glass out of the waste stream.

And the glass has the same properties for high heat storage as. Hm. I thought that was a really interesting, like here’s another element that ends up being part of the problem that we don’t know what to do with these things. Yep. And I wonder how many other unrecyclable materials could be utilized in this kind of, if you created almost a slurry of these materials in these kinds of canisters, could you in fact find a long term use to, well it’s we don’t know what we’re gonna do with it in 25 years, but right now it’s a battery.

Right.

Yeah. There’s not really directly to this video, but there was another comment. Another one of my videos about the amount of it’s called tailings mining tailings. There’s just basically like the leftover stuff. That’s like, oh, it’s a whole bunch of granite and another crap that nobody really wants.

Right. There’s a lot of leftover materials where it’s like today we’re finding, oh wait, you know, like enhanced weathering. We could actually take those mining tailings and actually use them for enhanced weathering on a farm. You know, it’s like, there’s all these different things that we’re discovering.

Oh, wait, that thing that we thought was junk and waste before could actually be used for something today. And it gives it a second life that we never expected. And so you you’re right. That, that idea of grinding up the glass back into kind of a, like a Silicon kind of material makes, makes a lot of sense.

It’s very clever.

Yeah. So listeners, do you think that sand is a part of the solution and one of the things that stands in the way of this, of course, as far as like district heating. Is our cities are largely, already. This is a kind of thing that you would have to figure out. Can you retrofit your city with this kind of tech is your community one that could actually accept that?

Let us know in the comments, jump into the comments, let us know if you live in a place where you think this kind of thing could actually find a home, or are you in a place like I am. I mean, New York city is not right now looking for yet another large scale project to add to the list, let us know in the comments.

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