The bigger picture: The Gemasolar solar plant generates electricity using molten salt.

OWNED BY Torresol Energy and developed by SENER, the Gemasolar solar thermal plant is the first facility of its kind in the world. The sprawling structure is capable of producing 80 GWh of clean and safe energy to 27 500 households annually. It’s located in the Spanish countryside in the village of Fuentes de Andalucía, about 66 km east of Seville.

The plant makes use of molten salt, which is heated in a central tower to a blistering 565°C by means of a surrounding heliostat field – a collection of mirrors that track the sun and reflect its radiation towards the receiver at the top of the tower. Assembled over seven months, there are 2 650 heliostats in total, distributed in rings around the tower. The furthest is positioned about 1 000 m from the centre. Each heliostat consists of a 120 m² reflective surface that is continually repositioned throughout the day, depending on the position of the sun and the prevailing weather conditions.

The Gemasolar tower itself is 140 m high and houses a unique component designed and patented by SENER: a high-efficiency cylindrical receiver, right at the top. The receiver is capable of absorbing 95 per cent of radiation in the solar spectrum, and of transmitting this energy to the molten salt compound, which circulates through the steam generator system. The steam drives a turbine, which, via an alternator, generates electric power.

The facility includes a storage system, enabling it to continue producing electricity for 15 hours without sunlight.