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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

#91

Post by yetihehe »

freddie_mercury wrote: post #87
m463 wrote: post #72

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was r…

> I get that sand is inexpensive It depends where you are. Sand thieves are a thing in many places around the world. Here's a story from 2015 about how residents in one area have lost 25 hectares of land to sand thieves. https://tuoitrenews.vn/news/features/20150524/residents-losi... Or a police captain whose legs were severed while trying to apprehend sand thieves. https://www.vietnam.vn/en/dien-bien-moi-vu-dai-uy-c…

For construction you need a special kind of sand (still pretty common on average). For this battery you can use sand unusable for construction.

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

#92

Post by kumarvvr »

freddie_mercury wrote: post #87
m463 wrote: post #72

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was r…

> I get that sand is inexpensive It depends where you are. Sand thieves are a thing in many places around the world. Here's a story from 2015 about how residents in one area have lost 25 hectares of land to sand thieves. https://tuoitrenews.vn/news/features/20150524/residents-losi... Or a police captain whose legs were severed while trying to apprehend sand thieves. https://www.vietnam.vn/en/dien-bien-moi-vu-dai-uy-c…

Sand used for construction should not have salt content.

For energy storage, any sand is sufficient.

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

#93

Post by standardUser »

foofie wrote: post #86
m463 wrote: post #72

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was r…

> But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. I think this is one of those things that drive home the point that there are fundamental differences between physics and engineering. The article states that the thermal silos are heated with excess energy from the power grid. This alone tells you right from the start that efficiency is not the primary requirement…

I can't endorse this perspective enough. The amount of energy storage we need is staggering and ever-growing. We've someone convinced ourselves that the 'baseline' is consuming with abandon millennia worth of stored energy and anything even slightly less responsive than that is too inconvenient. Given those parameters, we need any and all energy storage options and efficiency is not a priority. Tesla powerwalls were never going to power the world, but giant caverns full of sand might.

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

#94

Post by noqc »

fbdab103 wrote: post #64
noqc wrote: post #60

Earlier quoted context omitted.

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.

You could be right, insulation is a lot more effective at keeping houses warm than cold though (greenhouse effect) and heat pumps can dump their waste heat inside.

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

#95

Post by kwhitefoot »

freddie_mercury wrote: post #87
m463 wrote: post #72

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was r…

> I get that sand is inexpensive It depends where you are. Sand thieves are a thing in many places around the world. Here's a story from 2015 about how residents in one area have lost 25 hectares of land to sand thieves. https://tuoitrenews.vn/news/features/20150524/residents-losi... Or a police captain whose legs were severed while trying to apprehend sand thieves. https://www.vietnam.vn/en/dien-bien-moi-vu-dai-uy-c…

The article points out that it doesn't actually use what people usually think of as sand:

"The sand itself will also be sustainably sourced – it’ll consist of crushed soapstone, which is a manufacturing byproduct of another local industry."

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

#98

Post by yurishimo »

Gigachad wrote: post #49
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?

Less politically radicalised maybe? America should have all the tech and resources required to pull this stuff off, but it just doesn’t happen.

It's mostly centered around cost. Fuel (of all types) is so cheap in the US that efficiency was not an ultra high priority for most people. Ironically, the US has now gotten extremely competent at drilling for natural gas and the price is going to stay pretty much fixed where it is for the next 50+ years. Most of the waste from the early days has also been reduced and funneled into new petrochemical production processes that used to be reliant on oil.

If you are going to stay in one place for a long time, renewable solutions to problems like hot water and residential electricity are worth the investment, but with the migratory nature of the US worker, it's often cheaper for a household to pay for fuel for 5~ years rather than invest in a renewable solution that they will never reap the monetary benefits from.

From what I've experienced since moving from the US to Europe in 2022, it's a lot more common for people to stay in the same houses for an extended period of time. Especially here where I live in the Netherlands, you can commute to work almost anywhere in the country in about 2 hours by car. This allows people to keep the family home.

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

#99

Post by jillesvangurp »

freddie_mercury wrote: post #87
m463 wrote: post #72

I get that sand is inexpensive and simple and I like the idea - especially since it scales to an entire town (!) But I can't help but think of one "technology" that could make a scheme like this MUCH more effective. a phase change. for example, it takes 1 calorie for water to go from 30 to 31 degrees F, but but it take 80 calories to go from solid at 32 to liquid at 32 F. A project I remember reading about that was r…

> I get that sand is inexpensive It depends where you are. Sand thieves are a thing in many places around the world. Here's a story from 2015 about how residents in one area have lost 25 hectares of land to sand thieves. https://tuoitrenews.vn/news/features/20150524/residents-losi... Or a police captain whose legs were severed while trying to apprehend sand thieves. https://www.vietnam.vn/en/dien-bien-moi-vu-dai-uy-c…

> The sand itself will also be sustainably sourced – it’ll consist of crushed soapstone, which is a manufacturing byproduct of another local industry.

The requirement is not really construction grade sand but any substance with a largish thermal mass. Sand/dirt/crushed rock, etc. whatever you have right on your doorstep. There have been plenty of prototypes using such various materials as thermal mass.

All you need is a big container, some insulation to keep the heat in and lots of mass in whatever form. And some pipes to get heat in and out via e.g. water. The bigger the container, the smaller its surface area is relative to its volume. So these things can be quite efficient. If you make them large enough, you can store enough energy in the summer to last for months during the winter.

Here's a story about a Dutch retiree who built a prototype using basalt as the thermal mass in his backyard: https://deepresource.wordpress.com/2020/03/08/cesar-seasonal...

  Claimed performance:

  Storage volume: 200-250 kWh/m3

  Storage cost: 2 cent/kWh

  Storage leak: 80% energy still present after 6 months

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

#100

Post by bb123 »

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.

But this would stop you getting the sand hotter than 100c - which is one of the main advantages of using sand over water for heat storage.
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