Steam is converted into mechanical energy in a turbine, which powers a generator to produce electricity. A high-concentration solar tower panel that uses 200 mirrors to generate more than 500 kW of energy is capable of reaching maximum temperatures above 1000 °C. A tower solar power plant comprises a tall tower that supports a heat receiver surrounded by a field of heliostats that focus the sun's rays on the receiver. The power tower can be connected to a molten salt storage system, allowing the system to operate during periods of low or no incident solar energy.
The solar tower or central receiver type CSP system uses thousands of heliostats (large mirrors with individual monitoring) to concentrate solar radiation in a central receiver mounted on top of a tower. The first solar tower built in Spain in 1981 had 500 kW, and uses sodium as a heat transfer fluid. Since solar energy towers usually use steam to drive turbines, and water tends to be scarce in regions with a lot of solar energy, open wells tend to accumulate water since they have been excavated below the water table. The technology is still less developed than solar canalization technology, but about 30 such plants have been built, the largest of which has a gross generation capacity of 400 MW based on three solar towers.
An enormous number of mirrors focus solar radiation onto the tower receiver of a solar tower power plant. More specifically, these solar energy towers are external heat engines, since the heat source (the Sun) is separate from the fluid that moves and works. A portion of the energy produced during the first Rankine cycle was used through the electrolyzer to extract hydrogen. It is important to note that these solar energy towers are thermal engines, since they take energy from heat compared to their environment and convert that heat into movement.
While the cylindrical parabolic array uses a heat collection system distributed throughout the solar array, the solar tower concentrates heat collection in a single central installation. Heliostats are mounted on dual-axis solar trackers that track the Sun at the azimuthal angle and altitude angle in a way that reflects solar radiation and focuses on the solar energy receiver. There is a third design for a solar tower that could offer even better performance when using air as a heat transfer fluid. Therefore, the solar tower power generation system has a comparatively higher comprehensive optical energy conversion efficiency. The hot fluid is then used to boil water in a conventional steam turbine generator to produce electricity.
