The HEe boiler not only produces warm water for heating and tap water, it also produces electricity. It is actually a kind of small-scale power station. Before the commercial launch of the HEe, it is necessary to investigate whether the present electricity grid is suitable for it. On Het Kasteel estate in Apeldoorn, 170 HEe boilers have been fitted in homes which are all connected to the same distribution substation.

GasTerra is working with Nuon, Remeha, Alliander and Woonmensen Housing Association on this Smart Power City. It is a follow-up to the Weiland pilot, where a network with a high concentration of micro-CHPs was constructed in a hall.