
Zeolite retains heat indefinitely, absorbs 4x more heat than water - ukdm
http://www.extremetech.com/extreme/130523-zeolite-thermal-storage-retains-heat-indefinitely-absorbs-four-times-more-heat-than-water
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rcthompson
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:

Zeolite + water <-> Zeolite & water complex + HEAT

The reaction happens at the surface of the zeolite, so the storage capacity is
proportional to the surface area of the pellet. If you make the pellet highly
porous, this can be proportional to its volume.

~~~
eigenvector
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.

~~~
rcthompson
When you use water as a heat storage medium, you are storing the heat in the
kinetic energy of the water molecules. In common parlance, you are increasing
the temperature of the water. Obviously, over time the water's temperature
will gradually revert to the ambient temperature, and you will lose all the
heat you stored in it.

In contrast, when you store heat in Zeolite, you are not storing it as kinetic
energy, you are driving an endothermic chemical reaction that stores the
energy in high-energy chemical bonds. After you are done heating the Zeolite
to "charge" it, it will return to the ambient temperature, but it still has
(lots of) energy stored in the chemical bonds. This energy does not dissipate
in the way that the kinetic energy of a high-temperature substance would. The
energy can only be released by reversing the chemical reaction, so it is
securely stored. You can then transport the Zeolite at ambient temperature to
a location in need of heat, and then add water, which reverses the chemical
reaction and releases the heat again.

So it doesn't actually store "heat", it takes in heat (i.e. molecular kinetic)
energy and stores it in a different form (chemical bond energy).

~~~
kenrikm
So then it could be used to store heat created from a reactor then transported
where the heat is needed?

~~~
rcthompson
Yes, that is the general idea.

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mistercow
>By applying heat to Fraunhofer’s zeolite comes into contact with water, a
chemical reaction adsorbs the water and emits heat.

Parse Error: Unexpected verb "comes" on line 129.

~~~
JonnieCache
Also: "adsorbs."

EDIT: upon further research, I find that "adsorption" is actually also a
thing, but it appears that here they meant the traditional absorption.
Adsorbtion definitely isn't a thing. Also it sounds like a baby trying to say
"abortion," which is weird.

What possesses people to give things such similar names? And while we're at
it, mathematicians: stop using variables that rhyme. Bs, Cs, Ds, Es, Ps, Zs,
it makes my head hurt. Would it kill you to chuck an H or a Q in there? M and
N, now thats just purely vindictive. How am I supposed to cope with that?

After writing this comment I think the spelling part of my brain is now fried
forever. And to think I've been walking around merrily saying "absorbsion" all
these years...

~~~
creamyhorror
I learnt the verb "adsorb" in high school chemistry. Why is adsorption not a
thing? (Although it does look like the article meant "absorption" and not
"adsorption".)

Quote for those not in the know:

\-----

<<<"Absorb" refers to a situation where something is taken into a medium, and
disappears as a consequence (from?). "Adsorb" refers to a situation where
something gets stuck onto (to?) the surface of a medium.

We would use "absorb" for when light is absorbed by a coloured or opaque
object, or for when water is soaked into a sponge, or even for when my
students manage to "take in" some of what I am telling them. It is an ordinary
English word.

"Adsorb" is used for a very specific situation where molecules get stuck onto
a surface. It does not occur as a word in ordinary language, outside its
scientific meaning. Adsorption is very important, because many chemical
reactions can go a lot faster when the reacting molecules are adsorbed at a
surface (reactions of hydrogen gas on the surface of nickel, for example), or
chemical reactions can be prevented by the presence of a barricading adsorbed
layer on the surface (aluminium failing to react with air, for example), or
impurities can be removed from a solution by adsorbing them onto a finely
divided solid (activated charcoal for decolorizing solutions, or for medicinal
use, for example).>>>

~~~
JonnieCache
"adsorb" versus "adsorp."

Now you can see why my brain was fried trying to type all that correctly. Not
only do the phonemes sound the same, the letters are mirror images of each
other. I think I now know how dyslexics must feel all the time.

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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?

~~~
MaysonL
Actually, yes: water softeners use zeolites to remove various minerals from
the water. See this for an explanation:

<http://www.watervalue.com/watersofteners.html>

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nottwo
This reminds me of zeolite-water solar adsorption refrigeration:

This paper presents some of the experimental evaluations of a prototype solar
refrigerator, based on an intermittent thermodynamic cycle of adsorption,
using water as refrigerant and the mineral zeolite as adsorber. This system
uses a mobile adsorber, which is regenerated out of the refrigeration cycle
and no condenser is applied, because the solar regeneration is made in the
ambient air For the regeneration, a SK14 solar cooker is considered. The cold
chamber, with a capacity of 44 liters, is aimed for food and vaccine
conservation. The objective is to analyze the advantages and disadvantages of
the eventual use of this refrigerator in rural regions of Peru, where no
electricity is available. On the bases of the results obtained, a new
prototype of refrigerator for rural regions is designed, based on the same
thermodynamic cycle, but including changes in design and operation.

[http://fc.uni.edu.pe/mhorn/ISES2003%20(solar%20refrigeration...](http://fc.uni.edu.pe/mhorn/ISES2003%20\(solar%20refrigeration\).pdf)

During the day, solar energy is used to drive water out of the zeolite. The
dry zeolite is exposed to water under low-pressure causing the water to
evaporate and be adsorbed into the zeolite. The evaporative cooling can be
used to refrigerate food without electricity.

A German company with various zeolite refrigeration applications:

<http://www.zeo-tech.de/index_en.html>

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js2
Non-swipe link [http://www.extremetech.com/extreme/130523-zeolite-thermal-
st...](http://www.extremetech.com/extreme/130523-zeolite-thermal-storage-
retains-heat-indefinitely-absorbs-four-times-more-heat-than-
water?onswipe_redirect=no)

------
car
This german company is using silicagel in an air conditioning unit to cool
with heat: <http://www.sortech.de/sortech/forschung/> (site unfortunately in
german).

Edit: I just found another german company using heat for cooling, this one is
using zeolite: <http://invensor.com/en/technology/zeolite.htm>

------
debacle
> retains heat indefinitely

What are the physics behind that, because it sounds like it violates the laws
of thermodynamics.

~~~
olefoo
No, your conversion of ambient heat to drying the zeolite and the inverse
release of heat when adding water; are both less than perfectly efficient.
Entropy grows at each step. The retention of heat in the dried zeolite is not
a conversion step, and the total entropy of the system doesn't change during
that time.

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ccozan
Heat shield for spaceships? Imagine on re-entry the outside part is made of a
layer of zeolite, heat builds up but is retained on the layer and water is
released as vapours ( which can add an extra layer of shielding ).

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hosh
While industrial applications of this is useful, I think it is far more useful
to look at distributed manufacturing applications (such as RapRap + practical
zeolite heat batteries).

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ComputerGuru
Is this the same Fraunhofer Institute that owns the patents on MP3?

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ck2
Solar power storage for night/clouds - solved?

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

~~~
jerf
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 energy
difference between two temperatures of water for a given volume as well as the
next guy, but what temperatures, or is that even the right question? I'm
looking for someone who _knows_.)

~~~
hexagonal
The term of art you're looking for is "specific heat".

<https://en.wikipedia.org/wiki/Specific_heat>

The relevant number for water at 25C is 4.184 joules per gram. But this isn't
a strict apples to apples comparison: if you heat and cool zeolite in a vacuum
chamber, it'll have a pathetic specific heat. (Like perlite, another foamed
mineral, which has a specific heat of something like 0.1) That's because
there's a chemical reaction taking place, not pure dumb-matter heating or
cooling.

Meanwhile, the energy density of a lithium ion battery is 720 joules per gram,
and the energy density of gasoline is 47,200 joules per gram. This does not
"solve" energy storage, in any way, shape, or form.

~~~
ars
Someone downmodded you because you messed up your units.

It's 4.184 joules per gram _Kelvin_. Meaning it stores that much energy for
each dress of heat you add to it. If you take water from near freezing to
boiling that's 100 degrees of storage - meaning 418.4 joules per gram - which
is much more reasonable.

And there is no reason you have to stop at boiling. Storing something at 500
degrees is not impractical, so assuming starting at 20 degrees (room
temperature) you can store over 2000 joules per gram. And there are plenty of
materials that can handle even higher temperatures.

~~~
jerf
And that's a big part of my question... given that in the abstract water can
store any amount of heat (between absolute 0 and the point at which we can no
longer call it "water" due to being a plasma of some form), what exactly does
it mean for this material to be able to store 4 times as much?

I'm sure there's an answer, because I'm sure the journalist got that number
from somewhere, but I lack the connections to know where to begin finding this
information.

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ktizo
links to some relevant Fraunhofer pages;

[http://www.igb.fraunhofer.de/en/press-media/press-
releases/2...](http://www.igb.fraunhofer.de/en/press-media/press-
releases/2012/thermal-storage.html)

[http://www.igb.fraunhofer.de/en/competences/physical-
process...](http://www.igb.fraunhofer.de/en/competences/physical-process-
technology/heat-and-sorption-systems/thermal-storage-methods.html)

