14 ms·

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

178 points by ukdm 14y ago

ktizo 14y ago
So, assuming it is cheap and available, that's storage for solar power solved.
- ChuckMcM 14y 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.
  - ktizo 14y 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.
    - ChuckMcM 14y ago
      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.
      - ktizo 14y ago
        Was thinking of it more as an urban/industrial thing. Makes sense if you have to do power storage with this technology to do a lot of it at the street level if you can, rather than on the power generation site, as it gives you multiple redundancy and you have to supply cities with water anyway. So when you have excess electrical power you dry pellets. When you want power you give them water vapour which then gives you heat, which can give you motive power from heat engines, and from that electricity from induction generators. All three of which are needed in a typical urban environment, so you are not having to convert all the way back to electric for a large percentage of the power used. Now I know that this is not by any stretch the most thermodynamically efficient arrangement, but I suspect that it could be a relatively cheap and very robust approach that could store a hell of a lot of energy in a widely distributed network. [edit] looked into this a bit, and the temperature rise you tend to be able to achieve from adsorption in zeolite is not going to be enough to do anything much more than direct heating, from what I can find. On reflection, that should have been fairly obvious. Sulk. ;) http://engineering.ucsb.edu/~yuen/references/ref-2.pdf http://engineering.ucsb.edu/~yuen/references/ref-2.pdf
        ChuckMcM 14y ago
        No need to sulk :-) there are fun things you can do. So lets say you have this huuuuuge pile of zeolite, you put it in your back yard during the summer and dry it out, then you store it in your shed during the winter and use it to warm the house rather than gas, or wood, or electicity. Many climes are wet during the winter and dry during the summer so this works out well for the adsorbtion requirements, and you don't get the air quality guys on your case for burning wood in the winter time. That is a difference if these things can hold their energy potential for the 9 months between summer and winter.
        ktizo 14y ago
        No need to sulk I know, but I want there to be cool things that solve everything. And anyways, sometimes I enjoy sulking. Now excuse me while I go gather a huuuuuge pile of zeolite. :)
- jerf 14y 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.)
  - ktizo 14y 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.
  - hexagonal 14y ago
    The term of art you're looking for is "specific heat". https://en.wikipedia.org/wiki/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.
    - quantumstate 14y ago
      The specific heat is the energy needed to raise the temperature per mass. So for water it takes 4.184 joules per gram to raise the temperature by 1 kelvin. So if you heated water to 75 degrees you would have put in about 205 joules per gram. You then have to deal with conductive losses and the efficiency of a heat engine. This is not directly comparable to the energy density of gasoline or a lithium ion battery which use chemical reactions to store the energy. So you can turn almost 100% of the energy in a lithium ion battery into useful work but if you put the equivalent number of joules into heating an object you wouldn't get close unless you have a handy 0 kelvin object.
- Mvandenbergh 14y 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 14y 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.
  - ktizo 14y 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 14y 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 14y 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.
  - ktizo 14y 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 http://www.johnsonems.com/?q=node/2
rcthompson 14y 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.
- Splines 14y ago
  On that topic, does anyone know how these things work? http://www.amazon.co.uk/Magic-Gel-Reusable-Hand-Warmer/dp/B000MU4IJ2 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.
  - hexagonal 14y ago
    Sodium Acetate. https://en.wikipedia.org/wiki/Sodium_acetate https://en.wikipedia.org/wiki/Sodium_acetate
  - limmeau 14y 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)
    - vlisivka 14y ago
      Can I use sodium acetate to heat my energy passive home (which I will build soon) by heating it at day in Trombe wall and discharging it at night?
      - xutopia 14y ago
        It's most likely unwieldy. Sometimes you can cause the exothermic effect to occur without you wanting it by a vibration or shock.
mistercow 14y 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.
- ErrantX 14y ago
  Thank goodness I am not the only one for whom that sentence makes no sense!
- SoftwareMaven 14y 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.
- deleted 14y ago
  [deleted]
- JonnieCache 14y 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...
  - ErrantX 14y 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 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.
ktizo 14y ago
links to some relevant Fraunhofer pages; http://www.igb.fraunhofer.de/en/press-media/press-releases/2012/thermal-storage.html http://www.igb.fraunhofer.de/en/press-media/press-releases/2... http://www.igb.fraunhofer.de/en/competences/physical-process-technology/heat-and-sorption-systems/thermal-storage-methods.html http://www.igb.fraunhofer.de/en/competences/physical-process...
js2 14y ago
Non-swipe link http://www.extremetech.com/extreme/130523-zeolite-thermal-storage-retains-heat-indefinitely-absorbs-four-times-more-heat-than-water?onswipe_redirect=no http://www.extremetech.com/extreme/130523-zeolite-thermal-st...
deleted 14y ago
[deleted]
mdc 14y 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?
- MaysonL 14y 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 http://www.watervalue.com/watersofteners.html
debacle 14y ago
> retains heat indefinitely What are the physics behind that, because it sounds like it violates the laws of thermodynamics.
- olefoo 14y 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 14y 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).pdf 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 http://www.zeo-tech.de/index_en.html
ComputerGuru 14y ago
Is this the same Fraunhofer Institute that owns the patents on MP3?
ck2 14y ago
Solar power storage for night/clouds - solved?
car 14y ago
This german company is using silicagel in an air conditioning unit to cool with heat: http://www.sortech.de/sortech/forschung/ 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 http://invensor.com/en/technology/zeolite.htm
hosh 14y 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 14y 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 ).

178 points by ukdm 14y ago

ktizo 14y ago

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

ChuckMcM 14y 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.
- ktizo 14y 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.
  - ChuckMcM 14y ago
    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.
    - ktizo 14y ago
      Was thinking of it more as an urban/industrial thing. Makes sense if you have to do power storage with this technology to do a lot of it at the street level if you can, rather than on the power generation site, as it gives you multiple redundancy and you have to supply cities with water anyway. So when you have excess electrical power you dry pellets. When you want power you give them water vapour which then gives you heat, which can give you motive power from heat engines, and from that electricity from induction generators. All three of which are needed in a typical urban environment, so you are not having to convert all the way back to electric for a large percentage of the power used. Now I know that this is not by any stretch the most thermodynamically efficient arrangement, but I suspect that it could be a relatively cheap and very robust approach that could store a hell of a lot of energy in a widely distributed network. [edit] looked into this a bit, and the temperature rise you tend to be able to achieve from adsorption in zeolite is not going to be enough to do anything much more than direct heating, from what I can find. On reflection, that should have been fairly obvious. Sulk. ;) http://engineering.ucsb.edu/~yuen/references/ref-2.pdf http://engineering.ucsb.edu/~yuen/references/ref-2.pdf
      - ChuckMcM 14y ago
        No need to sulk :-) there are fun things you can do. So lets say you have this huuuuuge pile of zeolite, you put it in your back yard during the summer and dry it out, then you store it in your shed during the winter and use it to warm the house rather than gas, or wood, or electicity. Many climes are wet during the winter and dry during the summer so this works out well for the adsorbtion requirements, and you don't get the air quality guys on your case for burning wood in the winter time. That is a difference if these things can hold their energy potential for the 9 months between summer and winter.
        ktizo 14y ago
        No need to sulk I know, but I want there to be cool things that solve everything. And anyways, sometimes I enjoy sulking. Now excuse me while I go gather a huuuuuge pile of zeolite. :)
jerf 14y 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.)
- ktizo 14y 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.
- hexagonal 14y ago
  The term of art you're looking for is "specific heat". https://en.wikipedia.org/wiki/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.
  - quantumstate 14y ago
    The specific heat is the energy needed to raise the temperature per mass. So for water it takes 4.184 joules per gram to raise the temperature by 1 kelvin. So if you heated water to 75 degrees you would have put in about 205 joules per gram. You then have to deal with conductive losses and the efficiency of a heat engine. This is not directly comparable to the energy density of gasoline or a lithium ion battery which use chemical reactions to store the energy. So you can turn almost 100% of the energy in a lithium ion battery into useful work but if you put the equivalent number of joules into heating an object you wouldn't get close unless you have a handy 0 kelvin object.
Mvandenbergh 14y 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 14y 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.
- ktizo 14y 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 14y 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 14y 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.
- ktizo 14y 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 http://www.johnsonems.com/?q=node/2

rcthompson 14y 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.

Splines 14y ago
On that topic, does anyone know how these things work? http://www.amazon.co.uk/Magic-Gel-Reusable-Hand-Warmer/dp/B000MU4IJ2 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.
- hexagonal 14y ago
  Sodium Acetate. https://en.wikipedia.org/wiki/Sodium_acetate https://en.wikipedia.org/wiki/Sodium_acetate
- limmeau 14y 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)
  - vlisivka 14y ago
    Can I use sodium acetate to heat my energy passive home (which I will build soon) by heating it at day in Trombe wall and discharging it at night?
    - xutopia 14y ago
      It's most likely unwieldy. Sometimes you can cause the exothermic effect to occur without you wanting it by a vibration or shock.

mistercow 14y 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.

ErrantX 14y ago
Thank goodness I am not the only one for whom that sentence makes no sense!
SoftwareMaven 14y 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.
deleted 14y ago
[deleted]
JonnieCache 14y 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...
- ErrantX 14y 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 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.

ktizo 14y ago

links to some relevant Fraunhofer pages; http://www.igb.fraunhofer.de/en/press-media/press-releases/2012/thermal-storage.html http://www.igb.fraunhofer.de/en/press-media/press-releases/2... http://www.igb.fraunhofer.de/en/competences/physical-process-technology/heat-and-sorption-systems/thermal-storage-methods.html http://www.igb.fraunhofer.de/en/competences/physical-process...

js2 14y ago

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

deleted 14y ago

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mdc 14y 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?

MaysonL 14y 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 http://www.watervalue.com/watersofteners.html

debacle 14y ago

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

olefoo 14y 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 14y 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).pdf 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 http://www.zeo-tech.de/index_en.html

ComputerGuru 14y ago

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

ck2 14y ago

Solar power storage for night/clouds - solved?

car 14y ago

This german company is using silicagel in an air conditioning unit to cool with heat: http://www.sortech.de/sortech/forschung/ 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 http://invensor.com/en/technology/zeolite.htm

hosh 14y 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 14y 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 ).