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

http://www.extremetech.com/extreme/130523-zeolite-thermal-storage-retains-heat-indefinitely-absorbs-four-times-more-heat-than-water

by ukdm • 14 years ago

178 77 14 years ago

extremetech.com

ktizo9• 14 years ago

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

ChuckMcM3• 14 years ago

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 when this stuff would show up in the Edmund Scientifics catalog.

ktizo9• 14 years ago

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.

jerf2• 14 years ago

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.)

ktizo9• 14 years ago

Fair point. Although the exact energy per volume is a less important measure, given that we know the ballpark, than the energy stored per energy invested, and the maximum storage available when considered as a commodity in the market and resource availability.

hexagonal3• 14 years ago

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.

Mvandenbergh• 14 years ago

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.

tjmc• 14 years ago

Probably not. It's important to distinguish the storage of heat and power because the efficiency of converting heat into electrical power depends on how big the temperature difference between your heat source and ambient temperature is.

The easiest way to understand this is the formula for Carnot efficiency: 1-(Ambient temp/Heat temp) which is the maximum theoretical efficiency that can be extracted from a heat engine to do useful work (eg. produce electrical power)

So I don't know how fast this Zeolite releases heat, but let's say it does so gradually so that your working fluid only ever gets to 90 degrees C or 363K. The maximum Carnot efficiency on a 20 degree C (293K) day would be 1-(293/363) or around 19%. And that's the theoretical max - a practical engine would be much lower.

So if the Zeolite can release its heat fairly quickly at a much higher temp it could be useful for power generation, but basically it's more likely to be useful for releasing low level heat again when it's needed.

ktizo9• 14 years ago

Until I had a proper look at this, for some reason I thought you might be able to crank much higher temperature differentials out of the process.

Still, I prefer finding out that I am dreaming and being wildly optimistic, than to never bother dreaming or being wildly optimistic in the first place.

DeepDuh• 14 years ago

Let's do some math here, shall we. Oil has an energy density of 45MJ/kg. Water has a specific heat of about 4.2 J per gramm-Celsius. So if ambient=20C and heated water=100C we have 4.2*80 ~= 340 J/gramm => 340kJ/kg. These zeolites are claimed to have 4 times that capacity => 1.3MJ/kg.

Now we have yet another effect: The mass density of these zeolite balls is probably WAY below that of oil. Let's be generous and say it's a factor of 2. That means we would need 70 times the shipping volume of oil tankers to replace oil as our primary energy source. House tanks would need 70 times the volume. Car tanks would need 70 times the volume. Let's put it another way: For every liter of oil you use to transport them, you would need more than 70 liters of these transported JUST TO BREAK EVEN. I therefore heavily question whether this is useful even for the applications they claim. If anything they would have to be used very locally, not much more than the range we have today with isolated water pipers for transporting heat.

So yeah. These funny balls might be interesting for SOME applications, but they're far from being efficient enough for mass adoption.

anusinha• 14 years ago

The amount of energy you can store in this type of interaction is not very significant compared to other forms of solar storage. Batteries are one class of storage methods, but what's even better is to use solar energy to split water molecules and store it in molecular hydrogen and oxygen (H2 and O2). These can be recombined in a fuel cell to produce water (with no loss in molecules) and produce electricity. A much, much greater energy density, far greater than any existing battery would be in such devices.

Water-Splitting using natural sunlight is a difficult problem and many research groups at top institutions are working on it. The best known group in this field is Prof. Daniel Nocera at MIT. His research is being commercialized by the company Sun Catalytix and there are plenty of YouTube videos of him speaking and explaining his research. There are other research groups as well. The vision for the future is a distributed electrical grid. Each home or building would have a reactor on top that would contain a water-splitting catalyst producing hydrogen and oxygen gas, which can be stored indefinitely under pressure and then released into a fuel-cell device that would recombine to form water (that can be placed into the reactor) and electricity (for consumption). This would be an efficient way to capture much more of the sun's energy than current photovoltaics and is an entirely closed cycle.

ktizo9• 14 years ago

On a similar theme, I really like the work of Dr. Lonnie Johnson, better known for designing the supersoaker, on his weird cross between a heat engine and a fuel-cell that he calls a JTEC;

http://www.johnsonems.com/?q=node/2

rcthompson5• 14 years ago

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• 14 years ago

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.

dllthomas• 14 years ago

I assume it means that, because it is stored in the chemical structure rather than actual heat, it's not leaking to the environment while the pellet is sitting on a shelf (if not exposed to the elements).

mtmcannon2• 14 years ago

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.

MaysonL2• 14 years ago

Think of it as a rechargeable heat battery.

rcthompson5• 14 years ago

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).

Splines• 14 years ago

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.

hexagonal3• 14 years ago

Sodium Acetate.

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

limmeau• 14 years ago

I think there's a saturated solution of sodium acetate inside. The metal clickie causes the solution to crystallize, which happens to happen exothermically.

(IANAchemist)

excuse-me3• 14 years ago

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

excuse-me3• 14 years ago

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 a microwave system but then the inefficiencies are going to hurt.

Why not use one of the many phase change salt solutions that are also used for rechargeable heater packs?

Zaak• 14 years ago

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

gte910h• 14 years ago

A drum dryer like you use for clothing sounds built to take water out of these things (with grates smaller than the pellets of course).

rcthompson5• 14 years ago

Is it such a major problem that it leads to major efficiency losses (measured as joules of output energy over joules of input energy required to "recharge")?

nwmcsween• 14 years ago

> ..microwave system but then the inefficiencies are going to hurt.

What inefficiencies? A microwave should be more efficient due to it only energizing H2O bonds.

samstave2• 14 years ago

If they could use a similar process to how aerogel is made, creating a foam structure of the zeolite, then surface area would be considerable.

cheatercheater• 14 years ago

how is that stuff similar to the (salt?)-based cooling pads that you would crack to start the endothermic reaction, and then put in a freezer to "charge" them up?

mistercow2• 14 years ago

>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.

ErrantX2• 14 years ago

Thank goodness I am not the only one for whom that sentence makes no sense!

SoftwareMaven• 14 years ago

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

JonnieCache2• 14 years ago

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...

ErrantX2• 14 years ago

> but it appears that here they meant the traditional absorption

Sorry to add extra "fry" you your brain, but it appears they really did mean "adsorbtion" -> http://en.wikipedia.org/wiki/Zeolite

Which makes a lot of the science understandable. I can't help thinking that by saying "OMG hard science, so here is a massively dumbed down version" they actually made crucial parts of the theory incomprehensible :)

Case in point being; adsorbtion explains later comments about why surface area is important.

mistercow2• 14 years ago

>And while we're at it, mathematicians: stop using variables that rhyme. Bs, Cs, Ds, Es, Ps, Zs, it makes my head hurt.

I had a linear algebra teacher who was (I think) from Ukraine. Roughly all letters rhymed when he said them, and "a", "e", "i" were homophones.

creamyhorror• 14 years ago

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).>>>

narag• 14 years ago

What possesses people to give things such similar names?

Ad = To. Ab = From. That's Latin. People that invented it are long dead, so we have nobody to insult when we can't tell abductor from adductor.

ktizo9• 14 years ago

links to some relevant Fraunhofer pages;

http://www.igb.fraunhofer.de/en/press-media/press-releases/2...

http://www.igb.fraunhofer.de/en/competences/physical-process...

js2• 14 years ago

Non-swipe link http://www.extremetech.com/extreme/130523-zeolite-thermal-st...

mdc• 14 years ago

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?

MaysonL2• 14 years ago

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

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

debacle2• 14 years ago

> retains heat indefinitely

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

olefoo2• 14 years ago

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.

nottwo• 14 years ago

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...

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

ComputerGuru• 14 years ago

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

ck2• 14 years ago

Solar power storage for night/clouds - solved?

car• 14 years ago

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

hosh• 14 years ago

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).

ccozan• 14 years ago

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 ).

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

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