This project was an innovative system for the storage of residual heat in an aquifer at the University of Utrecht. By using heat storage, the number of operating hours of the heat and power installations during the summer period was increased as the heat produced was usefully employed. The stored heat was used during winter for space heating. As a consequence, less gas had to be used for space heating during the winter months and during summer less electricity had to be purchased. The degree of utilisation of the heat and power installations was increased, while the primary energy consumption was reduced.

The aim of the project was to demonstrate a practical applicability of heat storage in aquifers, in combination with combined heat and power installations in order to augment the useful exploitation of these installations. These installations were regulated on the basis of the heat requirements of the buildings of the university complex, which meant that at a reduced heat demand during summer, the installations were run at part load to avoid unprofitable production of excess heat. This led to a lower total yield of the heat and power installations and additional electricity also had to be purchased. As a result, residual heat in the form of water at a temperature of 90°C was stored in an aquifer and then used to produce electricity, which was used by the university complex. The stored residual heat was used in winter for the heating of a few buildings of the complex. In the feasibility study it was estimated that a thermal result (the heat stored which was then retrieved) of about 65% to 75% in the third year was achieved. At the realisation of the heat storage, additional data of the soil structure was obtained, thus soil structure could be represented better diagrammatically.