The first facility serving as an underground gas storage site in the Hungarian system was constructed near Őriszentpéter. From 1960, natural gas stored here contributed to meeting the peak demand of Budapest during the winter period. However, the continuous increase in the demand for natural gas made it necessary to establish further underground storage facilities. The programme started in 1977 with the conversion of the depleted working natural gas field in the area of Kardoskút, and was continued the following year by commissioning two further facilities in Hajdúszoboszló and Pusztaederics. Currently, Hungarian Gas Storage Ltd. owns and operates four underground natural gas storage facilities: Zsana, Pusztaederics, Kardoskút, and Hajdúszoboszló.