The tower power plants were originally based on the principle of water evaporation under the influence of solar radiation. Water vapor is used here as a working fluid. Located in the center of such a station, the tower has a water reservoir on top, which is painted black for the best absorption of both visible radiation and heat. In addition, the tower has a pumping group, the function of which is to deliver water to the reservoir. Steam, whose temperature exceeds 500 ° C, rotates a turbine generator located on the site of the station.

In order to concentrate the maximum possible amount of solar radiation at the top of the tower, hundreds of heliostats are installed around it, the function of which is to direct the reflected solar radiation exactly to the container with water. Heliostats are mirrors, the area of ​​each of which can reach tens of square meters.

Heliostat – A flat or focusing mirror element of an optical concentrating system, having an individual orientation device for directing reflected direct solar radiation energy to a solar radiation receiver.

Mounted on supports equipped with an automatic focusing system, all heliostats direct the reflected solar radiation exactly to the top of the tower, to the reservoir, as the positioning works according to the movement of the sun during the day.

On the hottest day, the temperature of the produced steam can go up to 700 ° C, which is more than enough for the normal operation of the turbine.

For example, in Israel, on the territory of the Negev desert, by the end of 2017, the construction of a tower power plant with a capacity of more than 121 MW will be completed. The height of the tower will be 240 meters (the world’s tallest solar tower at the time of construction), and around it there will be a floor of hundreds of thousands of heliostats, which will be positioned via Wi-Fi control. The steam temperature in the tank will reach 540 ° C. The $ 773 million project will cover 1% of Israel’s electricity needs.

Water is not the only thing that can be heated by solar radiation in the tower. For example, in Spain in 2011, the Gemasolar tower solar power plant was commissioned, in which a salt-based heat transfer fluid is heated. This solution made it possible to keep warm even at night.

The salt heated to 565 ° C enters a special reservoir, then transfers heat to the steam generator, which rotates the turbine. The entire system has a nominal capacity of 19.9 MW and is capable of supplying 110 GWh of electricity (on average per year) to power a network of 27,500 households, operating at full capacity 24 hours a day for 9 months.

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