Themis (solar power plant)

The THEMIS solar power tower is a research and development centre focused on solar energy. It is located near the village of Targasonne, in the department of Pyrénées-Orientales, south of France, 3 kilometres from the world's largest solar furnace in Odeillo. THEMIS solar power tower, owned by the General Council of the Pyrénées-Orientales, was strategically located in the region of Cerdanya, in the Pyrénées-Orientales, because the conditions are excellent for solar energy. First, Cerdanya has almost 2400 hours of sunshine a year; second, there is a very low wind limiting the time of disruption of the plant; third, the site is at a high elevation providing stronger sunlight. The land chosen for the plant is on a slope between 6° and 18°, which is suitable for a power tower. Research and development is focused on solar energy, and THEMIS is a research facility as well as a photovoltaic power facility and a solar thermal energy plant. The plant had a power output of 2 MW in 1983. It was based on an array of 201 mirrors which heated a cavity receiver (a cavity lined with coolant tubes) at the top of a 100 m tower where the coolant (molten salts) carried the thermal energy to a steam generator, itself powering an electric turbine. The molten salts were potassium nitrate (53%), sodium nitrite (40%) and sodium nitrate (7%). The coolant entry temperature was 250 °C and the exit temperature 450 °C. Steam was produced in the generator at a pressure of 50 bar and a temperature of 430 °C. The first THEMIS solar plant was an experimental solar facility which produced power between 1983 and 1986, and then closed in part due to the difficulty of managing the cooling system, and in part due to a lack of political and financial support. Construction started in 1979 at a cost of 300 million French francs (about 45 million euros), and was operated and managed by Électricité de France (EDF). The plant went into hibernation for more than twenty years, and turned into a scientific facility of the CERN, and the Commissariat à l'énergie atomique focusing on astrophysics, with an open air Cherenkov Telescope, measuring gamma rays hitting the atmosphere (see IACT).