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Zeolite retains heat indefinitely, absorbs 4x more heat than water

extremetech.com

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Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#21

Post by [deleted] »

jerf wrote: post #8
ktizo wrote: post #2

So, assuming it is cheap and available, that's storage for solar power solved.

I'd like to see some energy density numbers in units I can understand before I would jump up and down about this use. (I'm not saying you're wrong so much as saying I can't provide evidence you're right, and I'm hoping someone else can. Or at least tell us what exactly "the heat storage capability of water" is such that something can have 4 times as much. Please hold wild-assed guesses, please, I can compute the ener…

[deleted]

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#22

Post by samstave »

mtmcannon wrote: post #10
eigenvector wrote: post #5

Earlier quoted context omitted.

I don't see how this can translate to the title "Zeolite retains heat indefinitely". After the cycle of heating and cooling has been repeated some finite number of times, parasitic heat loss to the environment will eventually remove all of the heat added at the beginning.

What they mean is that when the Zeolite is "heated", then it can be stored indefinitely without "cooling down". If you heat water and put it in a tank, it will lose its heat relatively quickly. The Zeolite stores the energy from heat in (stable) chemical bonds, so it won't lose energy over time.

Can you give me some examples of how this can be used?

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#23

Post by excuse-me »

Splines wrote: post #14
rcthompson wrote: post #3

Short version of the science: The heat is released via an exothermic chemical reaction between the Zeolite and water. However, unlike the one-time-use chemical-reaction heating pads you can buy in a pharmacy, this reaction is reversible, so you can "recharge" the Zeolite by heating it and removing the water as it is released in order to force the reaction to reverse itself. The reaction goes something like this: Zeol…

On that topic, does anyone know how these things work? http://www.amazon.co.uk/Magic-Gel-Reusable-Hand-Warmer/dp/B0... I've seen them in person and they're remarkable if you've never encountered them before.

They are a supersaturated Sodium acetate solution. Liquids give off energy when they freeze and take energy in when they melt.

When you heat these and melt them they can stay stable as a saturated liquid until you create a small site for them to start freezing around - they then give off energy when they freeze. The 'clicker' is all that's required to localy concentrate it enough to form a single crystal seed to start the freezing

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#24

Post by ChuckMcM »

ktizo wrote: post #11
ChuckMcM wrote: post #6

Earlier quoted context omitted.

Not exactly but its a good start. But some interesting ideas come to mind. Using a conveyor to carry Zeolite to the top of a CSP plant and take the resulting stuff down to the reservevoir where its dumped into steam generators for turbines. If it replaced molten sodium as the working 'fluid' then that would make construction of such plants somewhat less challenging from an engineering perspective. I miss the days whe…

Why not exactly? Is basically decent heat storage and transfer with fairly low losses and minimal decay. Silos of these seem perfect for solar. Admittedly the big question, if you were going to rely on it, is whether there is enough zeolite globally to scale to the terawatt-hour range.

Not exactly because it doesn't change the design space of CSP, it just offers up a different heat storage mechanism.

To put it differently, if heat storage was the only problem with CSP, and there is already a heat storage solution available (liquid salt) then Zeolite isn't solving a known 'problem'.

You don't need 'indefinite' heat storage for CSP, you really only need a couple of days worth, and we have that already.

It might be interesting to look at the total economic cost of heating these things up in one place, transporting them, and then generating power there. However the heat capacity, even at 4x that of water, means that you've a constant stream of train cars dumping 'charged' pellets into your power plant. While another constant stream is carrying 'spent' pellets back to be recharged. Not to mention that for all of this to work you need to adsorb water so you end up effectively pumping water in the return path. In a CSP setup without a lot of water (say in the desert) this means you need some sort of vapor recovery mechanism to minimize the loss of water.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#25

Post by Zaak »

excuse-me wrote: post #16
rcthompson wrote: post #3

Short version of the science: The heat is released via an exothermic chemical reaction between the Zeolite and water. However, unlike the one-time-use chemical-reaction heating pads you can buy in a pharmacy, this reaction is reversible, so you can "recharge" the Zeolite by heating it and removing the water as it is released in order to force the reaction to reverse itself. The reaction goes something like this: Zeol…

Recharging it isn't that simple We use zeolite as a water scavenger in high vacuum systems, it's tremendously good at grabbing onto water BUT because it's so porous and very low thermal conductivity it's a real pain to heat it enough to get all the water out again. We have a heater resistor at the bottom of a small can of this and the top of the pellets a few cm away is cool enough to touch. You might do better with…

I wonder if you could incorporate a wire mesh into the zeolite to improve the heat distribution.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#26

Post by Mvandenbergh »

ktizo wrote: post #2

So, assuming it is cheap and available, that's storage for solar power solved.

That rather depends on how hot they get when you add water to them. Unless they get very, very hot indeed you're going to get rubbish thermodynamic efficiency generating electricity with them. I think these will be more useful for storing low temperature heat energy.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#27

Post by julian37 »

samstave wrote: post #22
mtmcannon wrote: post #10

Earlier quoted context omitted.

What they mean is that when the Zeolite is "heated", then it can be stored indefinitely without "cooling down". If you heat water and put it in a tank, it will lose its heat relatively quickly. The Zeolite stores the energy from heat in (stable) chemical bonds, so it won't lose energy over time.

Can you give me some examples of how this can be used?

The article gives one example: you could charge them with waste heat at plants and factories, then transport them to homes and offices where (I suppose) they could be used for heating and hot water, at some later point in time.

Sounds more efficient than teleheating via insulated pipes: http://en.wikipedia.org/wiki/District_heating

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#28

Post by mdc »

How selective is the zeolite in what it absorbs? Could this be used for water purification? That is, if you let the zeolite absorb water from an impure source, move it to a clean container and heat it to release the water, is the water potable? Even if it selectively absorbs water to remove contaminants, does the zeolite itself make the water non-potable?

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#29

Post by MaysonL »

eigenvector wrote: post #5
rcthompson wrote: post #3

Short version of the science: The heat is released via an exothermic chemical reaction between the Zeolite and water. However, unlike the one-time-use chemical-reaction heating pads you can buy in a pharmacy, this reaction is reversible, so you can "recharge" the Zeolite by heating it and removing the water as it is released in order to force the reaction to reverse itself. The reaction goes something like this: Zeol…

I don't see how this can translate to the title "Zeolite retains heat indefinitely". After the cycle of heating and cooling has been repeated some finite number of times, parasitic heat loss to the environment will eventually remove all of the heat added at the beginning.

Think of it as a rechargeable heat battery.

Re: Zeolite retains heat indefinitely, absorbs 4x more heat than water

#30

Post by mtmcannon »

samstave wrote: post #22
mtmcannon wrote: post #10

Earlier quoted context omitted.

What they mean is that when the Zeolite is "heated", then it can be stored indefinitely without "cooling down". If you heat water and put it in a tank, it will lose its heat relatively quickly. The Zeolite stores the energy from heat in (stable) chemical bonds, so it won't lose energy over time.

Can you give me some examples of how this can be used?

You can heat Zeolite using solar power during the day and release the energy at night. Current thermal energy storage techniques use stuff like molten salt (http://en.wikipedia.org/wiki/Thermal_energy_storage), which is a lot harder to work with than pellets.
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