Within this project, the current state of the art concerning thermal storage (both heat and coldness) was investigated and reported. Special attention went to commercially available solutions despite not all of them are integrated well yet (TRL starting from 6).

Some calculation methods and tools were developed to get a better sight on possibilities for heat or cold storage. Also the German partner GFaI is planning to integrate a thermal storage optimization tool within their commercial package TOP-Energy. UGent developed a tool as well to optimally dimensioning of cooling plants including a cold storage. However it seemed to be very difficult to develop a general easy to handle tool since there’re so many influencing parameters and storage systems could be very different as well.

In Flanders as well as in Germany a number of case studies was executed. Out of those about high temperature thermal storage to integrate in existing industrial processes, a common conclusion was because of the still historically low gas price already for a while being less than 20 EUR/MWh and the rather high specific cost (about 100 EUR/kWh) for thermal storage, pay back times starting from 8 and up to more than 10 years have been found, also too high following current industrial requirements. Anyway this is the case if the value of the recovered heat by storage is the only revenue.

However it seemed other profit models are possible. Probably a heat recovery installation (for instance an ORC) could be dimensioned to the average instead of to the maximum waste heat supply, also not losing any profits while the smaller installation, together with a thermal storage unit, probably doesn’t cost more compared to the peak dimensioned bigger installation.

Another option is to create flexibility by integration thermal storage within certain processes, for instance the possibility to uncouple electricity and heat generation on CHP-units or by transforming temporally excess supply of (renewable) electricity into heat for storage.

Within the involved lab of UGent Campus Kortrijk, in close collaboration with a German partner DLR, a unique demonstration for high temperature heat storage has been build. The storage tank is filled with 3,6 tonnes of a PCM (an eutectic salt mixture, melting at 222°C). Depending of the amount of used sub cooling and overheating the capacity is about 150-200 kWth. However it seemed the expansion of the PCM during melting is an important point of attention.

Finally, a lot of attention has been spend to dissemination. Beside some Dutch language publications several presentation on in and outlandish seminars, conferences or course series have been held. The own “5^th International Conference on Waste Heat Valorization”, this time completely directed to thermal storage and held on 21-22 May 2019 was the highlight. The program still can be consulted on www.wasteheat.eu.