Scientists of the German Fraunhofer Institute have harnessed a natural phenomenon to store heat indefinitely and without energy loss.
Zeolite is a mineral that can store up to four times more heat than water. And what’s better, unlike water which gradually cools off, zeolite retains a hundred percent of the heat for an unlimited amount of time.
Zeolite – which means ‘boiling stone’ in Greek- was named for its peculiar properties. Zeolite is extremely porous. So much so, that a gram of the stuff has a surface area of a 1000 square meters (10,764 sq ft). When water comes into contact with zeolite it is bound to its surface by means of a chemical reaction which generates heat. Reversely, when heat is applied the water is removed from the surface, generating large amounts of steam.
The transference of heat to the material does not cause its temperature to rise. Instead, the energy is stored as a potential to adsorb water. The Fraunhofer scientists used these particular properties to turn zeolite into a thermal storage system. They created a storage device and filled it with zeolite pellets. To charge the pellets, they exposed them to heat. To retrieve the energy they simply added water.
The discovery can give a much anticipated boost to thermal storage. Power plants and many industrial processes produce heat as a byproduct. Up to fifty percent of the initial energy input is released as heat.
But heat is difficult to store. The most common form of thermal storage is in huge insulated water tanks. But water can only retain heat for a short period of time which makes it unsuitable for long distance transport. Therefore, in most processes heat is released into the environment unused.
Although the unique properties of zeolite were well known, until now, no one was able to turn it into a working thermal storage system. The German researchers first tested their system with small quantities zeolite to determine whether the material would remain stable over multiple charge and discharge cycles. And it did. Even after thousands of cycles.
Now they’ve built an up-scaled version with a storage volume of 750 liters which they’re testing under realistic conditions.
Via: Igb.fraunhofer.de
About Tessel Renzenbrink
Tessel Renzenbrink holds an MA in philosophy and specialized in metaphysics. She writes about technology, energy and the changes in the cultural mindset that mark the shift towards the information age. 
Hi Tessel
Do you have a little more information on the heat storage properties of Zeolite. Most important, at what temperature does the phase change take place. For instance, Glauber salts (NaSO4.10H2O) changes phase at about 30 degrees which makes it useful for human space heating. A somewhat higher temperature is needed to put the heat back into the salt. Water undergoes its phase change, liberating latent heat at 0 degrees which makes it useless for space heating but great for refrigeration but not freezing (as you want when hanging meat or operating an ice box, for instance. What temperature does Zeolite operated at.
Regards
William
What is the price for that material? It sounds like it is useful, but can it be produced for a realistic price?
Hi William,
The paper The Rates of Solar Energy Storage and Retrieval in A Zeolite-water System [http://engineering.ucsb.edu/~yuen/references/ref-2.pdf] discusses the temperatures at which zeolite operates at length: “In the charging mode hot air is driven through a bed of zeolite particles of suitable size causing any adsorbed water to be expelled. This requires temperatures in the range 100-200°C depending on the degree of zeolite dryness required. In the discharge mode moist ambient air is driven through the bed, water vapour is adsorbed and the heat of adsorption is released. The bed temperature increases and the result is warm relatively dry air suitable for space heating.”
Hey Frits,
The zeolite thermal storage system isn’t cost effective yet. The next step of development is reducing production costs.
How bad that it`s not conductive – the super-capacitors need high surface area per volume to store charged molecules.
What is the upper limit of retrieved temperature?
Hi Tessel,
Thank you for the article. Do you know why, in spite of the reasonable temperature range, the technology has not picked up? Do you know the price of zeolite pellets? It would seem natural zeolite also works reasonably well … http://www.fao.org/docrep/T4470E/t4470e0j.htm