Energy storage
Mobility & Built Environment

Cellcius: the compact heat battery for energy storage

In cooperation with

TU/e, Cellcius

There is a great need for a compact and affordable device to store heat and energy. We are working on various technologies to achieve this, including thermochemical heat storage based on potassium carbonate. In order to market this technology, we set up a spin-off with TU/e: Cellcius.

To store heat in salt and then release it through a thermochemical reaction without losing energy is one thing. But to develop a technology and a device that allow this process to be applied in practice in a cost-effective way is an altogether different story. Especially on a larger scale, meaning in streets or even whole neighbourhoods.

Olaf Adan, professor at TU/e and principal scientist at TNO, has been working on such a total solution for energy storage with his research team for more than 10 years.

We have great ambitions. We believe that our heat storage solution can make a particularly important contribution to relieving heat and electricity networks at peak times. This is currently still a major bottleneck for the energy transition, so it feels good to be able to contribute to one of the possible solutions.

Olaf Adan - Professor at TU/e and principal scientist at TNO

This is how the heat battery works

The greatest challenge is the stability of the salt particles. When you add water vapour to salt crystals, they become larger, and heat is released. To then recharge the system, you not only have to separate the salt crystals from the water, but they also regain their original size. That's exactly what happens when you put energy into the heat battery. But with most salts, it isn’t possible to do this repeatedly. The salt particles start to clump together or fall apart.

High storage capacity

After years of experimentation with different types of salt and set-ups, the breakthrough followed in 2017. It became apparent that a specifically developed salt composite – with K2CO3 (potassium carbonate) as the base material – had the desired properties. When charged and discharged monthly, this salt composite remains stable and can last more than twenty years. And the storage capacity? This is many times greater than that of heat storage in water. As a result, you should be able to use it in a compact device.

Bonus: additional CO2 reduction

You can charge the heat battery with either heat or electricity, including with power from solar panels. In the process, no energy is lost, which makes this method of energy storage much more sustainable than, for example, using an electric home battery. But that's not all: the production of potassium carbonate requires CO2. So, it provides additional CO2 reduction.

Cellcius spin-off

The next challenge is to develop and market a compact, robust, and affordable energy storage device. A device that has a high efficiency in different situations and is also easy to install and use. To accelerate this development, we have set up a spin-off with TU/e, Cellcius, which works closely with industrial companies.

This collaboration is essential not only to market a device that meets the needs of users, but also to quickly scale up the production of both the devices and the required potassium carbonate. It appears that this solution will not only be suitable for use in individual homes, but particularly for heat storage at the street and neighbourhood level.

International demonstration project

Celsius has installed a prototype in a number of homes in Eindhoven, as well as in a number of homes in Poland and the south of France. This international demonstration project is partly funded by the European Commission. The project will shed more light on the effect of different types of climates and housing on the operation of the heat battery.

Market-ready products

At present, Cellcius is developing products for large-scale deployment at street and neighborhood levels. Products for deployment in homes are not yet provided for in the near future.

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