Dutch company launches heating battery: breakthrough for energy storage?

Wind farms or solar panels cannot continuously supply energy. Therefore, in a world where there is a growing dependence on green energy sources, energy storage technologies will become particularly important. Cellcius, a startup affiliated with Eindhoven University of Technology, is responding to this. The company has developed a battery that can store 70 kWh of heat. A period of a few energy-free days should thus be easily bridged.

Why is this important?

Worldwide demand for solar and wind energy continues to rise. Green energy has many benefits: for example, its widespread production can reduce our energy dependence on the fossil fuels of malicious geopolitical actors.

Utopias do not exist. An economy driven by green energy will inevitably also face challenges. What, namely, if the weather does not cooperate and you can not produce enough energy? Think, for example, of a lack of solar energy on light rainy autumn days, or a lack of wind on swell summer days. To cope with that problem, can you store some energy surplus during productive periods somewhere?

This can be done in two ways: the energy is converted into electricity, or stored as heat. Cellsius has chosen the latter with its heating coil. How does it work?

Thermochemical principle

The heating battery uses a thermochemical principle, suggests Cellsius CEO Evert Rietdijk. The battery is based on water and potassium carbonate, a salt hydrate that can bind to water. Addition of water vapor to the potassium carbonate creates a chemical reaction in which the crystals enlarge and heat is released. “The process is completely reversible,” says Rietdijk. “The moment I add heat, I evaporate the water again. I store energy in it. It (…) can be repeated indefinitely, it has already been repeated at least 250 times in our laboratories. “

closed circuit

The heating coil is actually one closed circuitinstallation with four main components, points out energy journalist Thijs ten Brinck. These components are as follows (watch videored.

  • a barrel full of salt grains, in this case potassium carbonate;
  • a fan that blows air through the salt grains and over the heat exchanger;
  • a condenser / humidifier that extracts or supplies water from the circulating air;
  • a heat exchanger that absorbs heat from an external heat source (by charging) or transfers it to a home (discharges).

source: TNO


The device will be tested in a first pilot later this year in four homes – two in Eindhoven and two in Poland and France. According to Rietdijk, a family with the battery should easily be able to survive “a few days” without renewable energy. With the pilot experiments, the researchers want to learn what it takes to implement the battery on a large scale.

Cellcius does not only want to heat individual homes with its heating coil. The Eindhoven company is also considering reusing industrial residual heat. For example, the startup wants to store residual heat from the Chemelot Campus in Sittard-Geleen, an industrial area filled with chemical factories, in the battery. This would then be moved to a “transformer house” in a residential area in the same municipality. That house should then supply about 50 homes with heat via pipes, you know Tweakers† This pilot phase was to start “within the next year”.


However, the project is not free of criticism. For example, the independent energy journalist Thijs ten Brinck has questions about the concept of “loss-free”, with which the company’s communications department presents the technology in the trade press. According to ten Brinck, the term is somewhat exaggerated, partly due to the energy loss during the cooling of the salt.


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