Solar Power Tower Plant
Solar Power Tower Plant CESA-1 (DLR) in Almeria (Spain).
Solar Power Tower Plant CESA-1 (DLR) in Almeria (Spain).

Solar power tower plants are large-scale industrial units generating electricity by converting solar heat. They are one of different kinds of Solar Thermal Electric Power Plants which are converting solar energy first to heat, then to electric power, while Photovoltaic Power Plants convert sunlight directly to electricity using Photoelectric Effects.

In a power tower plant the sunlight will be focused by a multitude of mirrors mounted on individual tracking systems (Heliostats) to one single receiver working as Heat Exchanger on a tower in the centre of the facility. The achievable temperatures – and therefore the thermodynamic efficiency – are significantly higher than with other types of solar power plants. Temperatures at the focus point can go beyond 1.000° C; depending on the heat transfer medium working temperatures between 500° and 1.300° C are strived for. While the first plants of this type used water steam as heat transfer medium, some of today's systems use heated air, but mostly liquid nitrate salts or sodium (which both can also be used as heat storage medium to provide heat and energy during the night). This heat transfer media will subsequently heat a working medium to drive steam or gas turbines generating electricity.

The power tower plant built in 2006 at Sevilla (Spain) represents the first business application of this technology in Europe. In the first operational stage of expansion it has the ability to produce 11 megawatts, slightly outperforming the by then biggest facility, the pilot project "Solar Two" in Califonia (10 MW). Within the second stage of expansion the construction of second tower with 20 MW is planned; including other technologies the final stage is planned to encompass a total capacity of about 300 MW of electric power.

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