They will enable industry to save on energy and costs. Using a Phase Change Material (PCM) is one attractive way of storing heat compactly with a small temperature difference. This entails using the quantity of latent heat that can be stored when a material melts and is released again when it solidifies. When a PCM is used, the heat buffer takes up less space, the heat is stored at atmospheric pressure, and the heat can be absorbed and released at a relatively constant temperature. The storage density of a PCM buffer is typically between 0.3 and 0.6 GJ/m3, making it up to four times more compact than a hot water buffer.

New possibilities for energy re-use and buffering

This technology offers new possibilities for re-using residual heat and saving energy in industrial processes. When a heat buffer is used, peaks in heat demand and supply can be counterbalanced to achieve a more constant process, supporting the use of sustainable heating and heat pumps. Heat storage also plays a connecting role in the integration of the electricity grid and the industrial heat supply.

ECN’s role

As part of the LOCOSTO project, ECN has developed a calculation model to predict the performance of a PCM buffer. The model optimises the design of the heat exchanger in order to achieve the required performance in the most cost-effective way. ECN is also working on the selection of PCMs with the desired characteristics for industrial applications, taking into consideration the melting temperature, heat storage density, stability, cost and safety and environmental aspects. One key technological challenge when using PCMs as heat buffers lies in the coupling and decoupling of heat when loading and unloading the buffer.

Test installation
A test installation with around 100 litres of PCM (see photo) is used to measure the performance of the storage and compare it with the model calculations. There is a high level of consistency between the experimental and model outcomes, providing a basis for the further development and scaling of PCM heat storage technology.