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Finnish City Inaugurates 1 MW/100 MWh Sand Battery

cleantechnica.com

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Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#41

Post by grues-dinner »

nick49488171 wrote: post #32
Cthulhu_ wrote: post #20

Earlier quoted context omitted.

To be pedantic, yes you can but you'd need to pressurize it to uuhh... According to this calculator [0], you can get water to 370 degrees C if the pressure is 207 atmospheres, which is about the pressure of the ocean two kilometers deep. [0] https://www.engineeringtoolbox.com/water-vapor-saturation-pr...

How many kiloton of TNT equivalent?

Well, if you say the energy stored is the 100MWh from the headline figure, and say you can arrange release every joule of all at once by flashing high-pressure water to steam at 1 atm that's about 0.1kT.

So quite a bang - allegedly this is 200lb, so about the same: https://www.youtube.com/watch?v=ZDgvar7ON54

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#42

Post by HPsquared »

jnsaff2 wrote: post #35
napoleoncomplex wrote: post #10

For anyone interested in a breakdown of the basic logic, this recent blogpost that trended on HN is probably the best: https://austinvernon.site/blog/standardthermal.html Really interested in seeing how it fares in reality, almost sounds too good to be true.

Why too good to be true? There are significant trade-offs with this technology. It's storing heat, so if you need electricity then you eat a lot of efficiency. I think Vernon said ~45% round trip efficiency. Batteries are 90%+. The storage is at a high temperature (500-600C) which means that you can't use heat-pumps to produce the heat to be stored. This means that you miss out on ~400% energy gains possible from con…

Yeah the efficiency is much less than 40% if you compare to heat pumps. It'll be something like 15% compared to those.

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#43

Post by internet_points »

privatelypublic wrote: post #38
internet_points wrote: post #14

Earlier quoted context omitted.

I learnt some new concepts here, specific heat capacity vs overall volumetric, things I kind of understood intuitively, but now much clearer: If I add some fixed amount heat to some fixed volume of water, it might rise by 1℃, while the same volume of concrete rises by 3℃. And by the same logic, on release, that fixed volume of water dropping by 1℃ releases 3x as much heat as when that fixed volume of concrete drops b…

Also to add some practicals: you can drive a steam turbine with the concrete temps, but not with the water. Also, looking at how hot water could theoretically get (decomposes between 2200-3300C), it looks like 1200C is an interesting limit. Above that and you get safety(practical) and cost issues with every material I could find (common salts, pure elements). Sand just makes sense! Though, don't ever youtube sand bat…

> don't ever youtube sand battery

Huh? I just get stuff related to this article?

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#45

Post by looofooo0 »

kitd wrote: post #12

I like these technologies. They may not be as energy efficient as using more exotic materials, but what they do use is simple, cheap and often sourced locally. Such economic factors are often as important to the ROI as the purely scientific ones.

I think with enough renewable in the grid, there will always be times when the costs are 0 or negative, so you can help stabilize the grid by consuming.

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#46

Post by grues-dinner »

vintermann wrote: post #17
isoprophlex wrote: post #5

Earlier quoted context omitted.

For this specific use case, you need to heat to far above the boiling point of water to retain some thermal efficiency. Sand/rock is better suited for storing the thermal energy at ~500 celcius.

I wonder if there are any chemical effects from heating the sand to 500 degrees Celsius. Finely roasted sand.

This is crushed soapstone, so it's mostly talc. Talc is apparently more or less stable up to about 800C, where it starts to break down into enstatite and silica: https://nvlpubs.nist.gov/nistpubs/jres/15/jresv15n5p551_A1b....

If it were pure silica sand, you could presumably get even hotter before anything changes chemically, but at the that point you start having materials issues with metal parts of the system: 500C is about the limit for ordinary steels to lose strength (and many are less than that - heat effects can often start at 300C).

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#47

Post by Tuna-Fish »

fulafel wrote: post #4

It doesn't list the advantages over water, which seems the most common in https://en.wikipedia.org/wiki/Thermal_energy_storage systems. You'd think water would be easier to exchange heat with since it can slosh around the heat exchanger elements in the tank more easily. Which should translate to lower costs since you don't need as many exchanger structures in the medium. Any guesses for the motivation in using sand?…

> But then big heat differences to the environment mean high conductive/radiation losses or heavier insulation requirements.

Square cube scaling means that insulation becomes trivial in total costs as you scale the installation up. Something that's convenient for a single household would probably be too hard to insulate, but this thing holds 2000t of sand.

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#48

Post by lysace »

diggan wrote: post #37
pintxo wrote: post #31

Really like the idea, but my house alone has roughly 16 MWh/a heat consumption. Of which half gets consumed November through January. So this system could supply 12 houses? Shows the importance of proper insulation, which is still on our todo list.

Sweden seems to have some of the highest "Electricity consumption per dwelling" ( https://www.odyssee-mure.eu/publications/efficiency-by-secto... ) in Europe, and sits at 10 MWh, which makes sense, it's a very cold country but with very well isolated houses in general :) It sounds to me like you're likely an outlier here, for curiosities sake, where do you live?

16 MWh of electricity/year isn’t really an outlier for an electrically heated (via efficient heat pumps) house in Sweden either.

Your number above probably includes apartments and houses heated using district heating, e.g. from incinerating forest industry waste products.

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#49

Post by stavros »

privatelypublic wrote: post #38
internet_points wrote: post #14

Earlier quoted context omitted.

I learnt some new concepts here, specific heat capacity vs overall volumetric, things I kind of understood intuitively, but now much clearer: If I add some fixed amount heat to some fixed volume of water, it might rise by 1℃, while the same volume of concrete rises by 3℃. And by the same logic, on release, that fixed volume of water dropping by 1℃ releases 3x as much heat as when that fixed volume of concrete drops b…

Also to add some practicals: you can drive a steam turbine with the concrete temps, but not with the water. Also, looking at how hot water could theoretically get (decomposes between 2200-3300C), it looks like 1200C is an interesting limit. Above that and you get safety(practical) and cost issues with every material I could find (common salts, pure elements). Sand just makes sense! Though, don't ever youtube sand bat…

Why not YouTube sand battery? I did it, and nothing much happened.

Re: Finnish City Inaugurates 1 MW/100 MWh Sand Battery

#50

Post by arowthway »

This is super cool but the ending is bizarre.

> A comment on the YouTube video below complained, “Not a word about return on investment in the presentation. That means it’ll never pay off” MAGAlomaniacs are everywhere these days.

Given the supposed 50+ year lifespan of such a battery, I find it hard to believe it doesn't turn a profit at some point. And I understand that debunking low-effort accusations is asymmetric warfare. But why cite a random YouTube comment if you have no intention of addressing its claims? A more charitable interpretation is that it's meant to ragebait the readers. But to me, it seems like trying to make people feel ashamed for having doubts, by making a public example of a skeptic.

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