The Andasol solar power station is a 150-megawatt (MW) concentrated solar power station and Europe's first commercial plant to use parabolic troughs. It is located near Guadix in Andalusia, Spain, and its name is a portmanteau of Andalusia and Sol (Sun in Spanish). The Andasol plant uses tanks of molten salt as thermal energy storage to continue generating electricity, irrespective of whether the sun is shining or not. Description Andasol is the first parabolic trough power plant in Europe, and Andasol 1 went online in March 2009. Because of the high altitude (1,100 m) and the semi-arid climate, the site has exceptionally high annual direct insolation of 2,200 kWh/m2 per year. Each plant has a gross electricity output of 50 megawatts (MWe) and 49.9 MWe net, producing around 165 gigawatt-hours (GW·h) per year. The collectors installed have a combined surface area of 51 hectares (equal to 70 soccer fields); it occupies about 200 ha of land. Andasol has a thermal storage system which absorbs part of the heat produced in the solar field during the day. This heat is then stored in a molten salt mixture of 60% sodium nitrate and 40% potassium nitrate. This process almost doubles the number of operational hours at the solar thermal power plant per year. Each unit fully loaded storage system holds 1,010 MW·ht of heat, enough to run the turbine and produce electricity for about 7.5 hours at full-load, in case of overcast skies or after sunset. The heat reservoirs each consist of two tanks measuring 14 m in height and 36 m in diameter and containing molten salt. Andasol 1 is able to supply environmentally friendly solar electricity for up to 200,000 people. Andasol consists of 3 projects: Andasol-1 (completed 2008), Andasol-2 (completed 2009) and Andasol-3 (completed 2011). Each project generates approximately 165 GW-h each per year (a total of 495 GW-h for all three combined). The total cost of building the three projects was estimated to €900 million. Rationale Andasol 1 cost around €300 million (US$380 million) to build. Thermal energy storage costs roughly US$50 per kWh of capacity (150 lbs of salt per kWh at a storage temperature of 400 °C), according to Greg Glatzmaier of the U.S. National Renewable Energy Laboratory (NREL), totaling about 13% of Andasol's initial cost. The developers say Andasol's electricity will cost €0.271 per kilowatt-hour (kW·h) to produce. Under current government policy in Spain, solar-thermal