Dr Hans Boumans
- Director Technology Transfer
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If we are to achieve a future in which all energy is generated sustainably, then the ability to store heat – in particular – is crucial. After all, the sun does not always shine, and the wind does not always blow. Together with the Eindhoven University of Technology, TNO has succeeded in developing a unique material and a compact device for domestic heat storage. What makes this battery special is that it can store large amounts of heat for use when other sources are not available. It is also much cheaper than more conventional solutions.
We’re not quite there yet, but experiments in the lab have shown that the ‘closed-loop’ system does work. Over the next two years, it will be a question of refining the device into a ‘plug-and-play’ version that can be easily accommodated in a home. Its various components – a reactor, a heat exchanger, an evaporator/condenser, and a fan – need to fit into a casing the same size as a domestic refrigerator. Such a device would contain sufficient heat for an average family to take daily showers for periods of up to two weeks when the sun is not shining or the wind is not blowing.
The invention, for which a patent has now been granted, is based on a thermochemical principle. The researchers experimented with a salt hydrate (potassium carbonate), which reacts with water to form a new compound. When water vapour is added to the salt, a chemical reaction is triggered. This causes the properties of the crystals to change, releasing heat. The process is completely reversible. When water is removed from the salt crystals, heat is stored in the salt. These cycles of storing and releasing heat previously caused the crystals to ‘wear out’. However, the experts have now solved this problem. They have created a stable salt particle that is capable of repeatedly storing and releasing heat without loss.
The planned device can be powered either by electricity or by heat, from a range of renewable energy sources such as solar- or PV collectors, and heat pumps. The big advantage is that a great deal of heat can be stored in a relatively small volume, and that this loss-free source can supply homes with heating and hot water when required. Relatively little energy is needed to run this system. Another plus is that the device boosts the efficiency of heat pumps and solar collectors, while smoothing out any peaks in the power grid. At this stage, this system could be used in homes for less than one tenth of the cost of current electric batteries.
The market for this technology is huge. Millions of homes could be fitted with this system in the Netherlands alone, and many times that amount in the EU as a whole. This holds out two huge opportunities for the Dutch business community. The first of these involves the production of the salt composite. Incidentally, this requires CO2, which makes it even more attractive. Furthermore, the new heat battery needs to be produced and launched onto the market as soon as possible. In this area, the Netherlands can play a pioneering role at international level.
TNO and the Eindhoven University of Technology would be happy to engage with investors and with any companies that are prepared to develop this innovative product in a very short timescale.