The country's main primary source of electrical power is Elektrėnai Power Plant. Other primary sources of Lithuania's electrical power are Kruonis Pumped Storage Plant and Kaunas Hydroelectric Power Plant. Kruonis Pumped Storage Plant is the only in the Baltic states power plant to be used for regulation of the power system's operation with generating capacity of 900 MW for at least 12 hours. , 66% of electrical power was imported. First geothermal heating plant (Klaipėda Geothermal Demonstration Plant) in the Baltic Sea region was built in 2004.