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Giant 'sand battery' holds a week's heat for a whole town

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Re: Giant 'sand battery' holds a week's heat for a whole town

#61

Post by komali2 »

anonu wrote: post #44

It feels that Europe is so far ahead the US in matters of environmental sustainability. Why is that? Is it more dense than the US, so they need to be more careful with resources?

Europe is more politically progressive (in some ways) than the USA, and sustainability is a progressive standpoint. Political identity politics in the USA means that even if you have a ranch in rural Texas and are directly observing the negative effects of fracking on your local environment, you still support the people that are trying to make more of that happen because if you don't, well, you must hate pickup trucks and beer and Christians too (drawing on personal experience as a Texan).

I've poked around on this topic here and there when bored and never found many good explanations for why this is the case. Probably a million weird little reasons, historical, economic, cultural. IMO the country is just too damn big to try to claim a single cultural identity, and it's resulted in absurd caricatures of polarized political identity, fostered as well by a two party system where it's basically impossible to be represented well per your values. In the USA you can't vote for someone that's promoting reducing government spending without also voting for someone that's attacking trans people's right to exist, or at least in the same party as such a person. Or someone that's trying to take away your wife's healthcare rights. Same way you can't vote for reducing oil dependence without also voting for, idk, taking everyone's guns away.

Re: Giant 'sand battery' holds a week's heat for a whole town

#62

Post by llm_trw »

komali2 wrote: post #58
llm_trw wrote: post #33

Earlier quoted context omitted.

Just because something seems like should work doesn't mean it will. Air conditioners are simple and cheap to install. An insulated swimming pool in the basement is not.

> Air conditioners are simple and cheap to install Today. In my chats with the sort of home improvement types that seem to be in this thread, we're less concerned with today and more concerned with the cost of things in the future, as societies include "climate taxes" (in the form of actual taxes, subsidies, or whatever else) in the cost of things.

And tomorrow because when you want to cool your house the sun is most likely out.

Re: Giant 'sand battery' holds a week's heat for a whole town

#63

Post by tonyarkles »

candiodari wrote: post #17
SuperNinKenDo wrote: post #14

Earlier quoted context omitted.

In addition to what others have said, isn't one of the weird properties of water that it tends to take in energy easily, but not give it back so easily? I've never really understood how that works, but I think I've leqrned that at some stage. Hence why it's used in cooling so much. Somebody jump in and tell me how wrong I am, or if I'm on a track that doesn't lead completely nowhere.

Water vaporizes, and at that point blows up just about every container you can build around it. As will ice when it cools down. Sand is just sand, very little difference, very unreactive from way under freezing temps to about 1300 degrees. And you might vent steam, but you should probably take into account that while water < 45 degrees or so is pretty innocent, steam will strip flesh from bone starting at 180 degrees…

That’s the other bizarre thing about water/ice: most things expand as you heat them, but very few things expand as you cool them. Water has maximum density at 4C, so even before you freeze it it’s already starting to expand as you cool it.

Re: Giant 'sand battery' holds a week's heat for a whole town

#64

Post by fbdab103 »

noqc wrote: post #60
bicebird wrote: post #25

I was thinking of ways to get around the peak solar generation being when you don't need it for heating and genuinely really heartening to hear about solutions like this. The article doesn't mention the costs or complexity in building each unit but definitely implies it's cheaper than storing it batteries, which makes sense if it's essentially a heating element buried in sand. Wonder what the smallest viable size wou…

Peak solar is peak A/C usage in the summer, which is typically more expensive than heating. In colder times more energy is used at night, but I think less energy is still used at night in the winter than in the day in summer.

That does not seem right.

A hot day in summer might be 35C->20C (95F->68F). Winter is going to be more like -10C->20C (15F->68F) twice the temperature gradient to overcome.

Re: Giant 'sand battery' holds a week's heat for a whole town

#65

Post by fy20 »

Karellen wrote: post #9

Something similar, but more for industrial processes: Can a Simple Brick Be the Next Great Battery? | John O'Donnell | TED https://www.youtube.com/watch?v=X6Wgd4v_yW8

This is basically how houses in central Europe work. The walls and floors are built with masonry (bricks or concrete) and wrapped in a thick layer of insulation. This results in a building with a very high thermal mass.

The result is that it takes a long time for the inside of the building to change temperature.

The other day we had a warm sunny spring day (5C / 40F), so I opened all the windows and did some spring cleaning. I set the thermostat to 16C as I didn't want the heating coming on while I was doing this.

I forgot about this, and the next day when I woke up wondered why the temperature in the house was only 20.5C (68F) as usually we have it set to 22C (72F) - then I remembered I effectively turned off the heating 18 hours ago, and forgot to turn it back on.

Re: Giant 'sand battery' holds a week's heat for a whole town

#66

Post by dragontamer »

bumby wrote: post #48
dragontamer wrote: post #41

Earlier quoted context omitted.

It definitely seems economically viable to me I'm hoping someone recreates it. It's just a few fans, a tub of water, a pump, and a slightly modified heat pump/air conditioner unit that can safely run down to 50F or so. It's already viable for stadiums and other public events.

This has been around for a long time. The Detroit VA hospital used it, I believe with tanks under the parking structure. I also believe there were problems related to the maintenance of the tanks. But the important aspect is that this is a cost saving technique, not an energy saving one. You’ll spend more energy because of the thermal losses of the tanks, but hopefully it is more than offset by the cheaper electricit…

Energy is (sometimes) free, or even negative priced (!!!!).

As it turns out: it's economically infeasible to turn off solar panels, wind, nuclear and sometimes Hydro (depending on water rights, it may be illegal to store water/energy at a water dam).

In all of these cases, the energy is 0 cost or even negative cost.

Re: Giant 'sand battery' holds a week's heat for a whole town

#67

Post by lancewiggs »

gorpy7 wrote: post #35

Ben_bai said it pretty well. water is good but it can cause rust, pressure, freeze, leak, etc. sand avoids most of this. the big thing is that sand can be heated much much hotter and this helps make up for its shortcomings relative to water. they likely charge and discharge with air blowing thru stainless steel network of pipes thru the sand. this would require special tuning. as someone else mentioned, the thing wit…

MGA Thermal uses tiny aluminium droplets in carbon matrix material to do heat storage with 1: constant temperature storage and 2: at much higher temperatures and energy density that allows for steam generation etc.

Re: Giant 'sand battery' holds a week's heat for a whole town

#69

Post by mercutio2 »

immibis wrote: post #46
Valgrim wrote: post #43

Earlier quoted context omitted.

Some Youtube folks tried a much simpler approach: Take a large metal bucket or barrel. Put a heating element and a simple oven thermostat on the bottom. Fill with sand. Connect to a solar panel or other enrgy source. The air between the sand particles seem to actually provide a bit of convection and insulation. The thermostat turns the circuit off before getting too hot for the heating element. The heat accumulated d…

Any system that involves an electrical solar panel connected to a low-temperature electrical heater is likely to be better served with a solar hot water panel, by about a 10:1 ratio.

Are you including the maintenance costs of the water panel in your estimate?

I used to buy this argument, but then:

A) PV panels got ridiculously cheap

B) everyone I know with solar hot water has emptied their systems because the maintenance hassles were not worth dealing with

Using high grade intermittent current to produce resistive heat isn’t high on my list of efficient things to do, but unfortunately neither is maintaining hot water panels.

Re: Giant 'sand battery' holds a week's heat for a whole town

#70

Post by palmfacehn »

mercutio2 wrote: post #69
immibis wrote: post #46

Earlier quoted context omitted.

Any system that involves an electrical solar panel connected to a low-temperature electrical heater is likely to be better served with a solar hot water panel, by about a 10:1 ratio.

Are you including the maintenance costs of the water panel in your estimate? I used to buy this argument, but then: A) PV panels got ridiculously cheap B) everyone I know with solar hot water has emptied their systems because the maintenance hassles were not worth dealing with Using high grade intermittent current to produce resistive heat isn’t high on my list of efficient things to do, but unfortunately neither is…

The most I've had to do is clear the dust from the tubes during the dry season.
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