Gas consumption is variable according to the time of day or year. Less gas is needed in summer than in winter and more during the day than at night. The gas supply must be adaptable to this. For decades, fluctuations in supply have been mainly accommodated by the Slochteren field near Groningen which has unique geological features. However, the pressure in the Slochteren field is falling making it more difficult to deliver gas rapidly. That’s why gas storage facilities are becoming increasingly important in order to be able to guarantee a reliable gas supply for heating homes and districts, powering industry and generating electricity.