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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

#31

Post by llm_trw »

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…

>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.

Batteries are more expensive than nuclear power so yes, anything else is better.

The issue is that we can't both electrify everything and use legacy heating applications. Going back the the 20th century idea of central heating/cooling is great until you realize the costs involved with adding all the plumbing to buildings which were never designed with it in mind.

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

#33

Post by llm_trw »

0cf8612b2e1e wrote: post #23
dragontamer wrote: post #4

Earlier quoted context omitted.

IceBear went out of business with the opposite tech: tanks of water storing the cold generated from excess AC cycles. Cheap electricity can make cold, and then a fan can convert the cold water into cold air during peak hours when electricity was costlier. Fans still took electricity to run, but it'd only be a few hundred watts to run air-conditioning rather than kilowatts of power.

How long ago was this? The idea seems simple enough and would really benefit from the increasing glut of renewables. Even better, unlike a sand battery, you can potentially cycle it for several months of summer, by offsetting consumption by just a few hours feels like it could be economically viable. Then again, the competition is general purpose batteries which can be used all year and probably require less maintena…

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.

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

#35

Post by gorpy7 »

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 with water is that the temp is uniform everywhere because water transfers heat within its volume easily. sand doesn’t, so you need pipes spaced out right. i’ve wondered about insulation but, i think you can step it out with refractory bricks first then a mineral insulation, then something like perlite or fiberglass. the hot air would interface with heat exchanger to transfer the heat to whichever fluid that would go on to heat the home/s. since the sand can be heated to 1700F or more, a kiln or quartz heating element that can exceed this temp is needed. last, a thermally isolated heat temp tolerance fan would be required. i guess a slew of sensors in the sand and at the exchanger unit and output, i can imagine wanting sensors everywhere for tuning sake.

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

#36

Post by reaperman »

noqc wrote: post #24
Animats wrote: post #21

This new sand battery is expected to stand 13 m (42.7 ft) tall and 15 m (49.2 ft) wide, providing an output power of 1 MW and a capacity of 100 MWh. That's impressive. It's close to the energy density of fuel oil. Or did I calculate that wrong?

100 MWh is 8 tons of "oil", according to a google search. Oil is probably about the density of water, so 1 cubic meter is about 1 ton of oil, and this structure is about 2000 cubic meters, so oil has 200 times the fuel density of this battery. It's still pretty good though.

“Oil” is 10-15% less dense than water. So yes, “about” the density of water, for napkin purposes. This would be diesel or heating oil.

Gasoline is 30% less dense than water though.

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

#37

Post by logtempo »

noqc wrote: post #24
Animats wrote: post #21

This new sand battery is expected to stand 13 m (42.7 ft) tall and 15 m (49.2 ft) wide, providing an output power of 1 MW and a capacity of 100 MWh. That's impressive. It's close to the energy density of fuel oil. Or did I calculate that wrong?

100 MWh is 8 tons of "oil", according to a google search. Oil is probably about the density of water, so 1 cubic meter is about 1 ton of oil, and this structure is about 2000 cubic meters, so oil has 200 times the fuel density of this battery. It's still pretty good though.

your number is good, as it's the heavier from all oil. Don't work for all type of oil though.

https://en.wikipedia.org/wiki/API_gravity

    Light crude oil has an API gravity higher than 31.1° (i.e., less than 870 kg/m3)
    Medium oil has an API gravity between 22.3 and 31.1° (i.e., 870 to 920 kg/m3)
    Heavy crude oil has an API gravity below 22.3° (i.e., 920 to 1000 kg/m3)
    Extra heavy oil has an API gravity below 10.0° (i.e., greater than 1000 kg/m3)

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

#38

Post by chiph »

pfdietz wrote: post #15

NREL's ENDURING sand battery, storing heat at 1200 C in quartz sand. Round trip efficiency using turbines is estimated at ~53%. https://arpa-e.energy.gov/sites/default/files/2021-03/07%20D... The IP has been licensed by Babcock and Wilcox, who are the source of the nifty compact fluidized bed heat exchanger.

It's an interesting concept. Cheap. Doesn't take up a lot of space. Could be driven by a solar furnace.

My concern is whether the cyclone particle separator will do a good enough job - gas turbine blades don't like being blasted with grit. I expect they'd need a heat exchanger to be sure to get only clean gas driving the turbines.

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

#39

Post by logtempo »

gorpy7 wrote: post #3

This is great technology, simple and effective. I’ve spent many hours reverse engineering to see how effective and expensive it might be. I’ve found it’s very cost effective but heat can be hard to calculate. i like that they did a prototype. i think i’ll do one at some point. for an individual house it makes more sense to improve my insulation but i think ill still build a small version for fun.

it's how "rocket stove" works: https://en.wikipedia.org/wiki/Rocket_stove

Since you burn the wood really fast, you need to delay that heat release. That's where sand comes in as a cheap and good enough material. There are also systems that heat water and store it in a tank, which also make sense if you want hot water in your house too.

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

#40

Post by abkfenris »

dragontamer wrote: post #4
gorpy7 wrote: post #3

This is great technology, simple and effective. I’ve spent many hours reverse engineering to see how effective and expensive it might be. I’ve found it’s very cost effective but heat can be hard to calculate. i like that they did a prototype. i think i’ll do one at some point. for an individual house it makes more sense to improve my insulation but i think ill still build a small version for fun.

IceBear went out of business with the opposite tech: tanks of water storing the cold generated from excess AC cycles. Cheap electricity can make cold, and then a fan can convert the cold water into cold air during peak hours when electricity was costlier. Fans still took electricity to run, but it'd only be a few hundred watts to run air-conditioning rather than kilowatts of power.

My local power company worked with a bunch of businesses in my town to install these rather than upgrade the dead end line for a few peak periods.
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