Environmental Engineering Reference
In-Depth Information
Steam generator
and superheater
Parabolic trough
collector field
Storage
Parallel
heater
Turbine
Generator
Solar
circulation
Water-steam
circulation
Pump
Pump
Condenser
Cooling
tower
Figure 1.10
Principle of a Parabolic Trough Solar Power Plant
One important advantage of solar thermal power plants is that they can
operate with other means of water heating and thus a hybrid system can ensure
security of supply. During periods of insufficient irradiance, a parallel burner
can be used to produce steam. Climate-compatible fuels such as biomass or
hydrogen produced by renewable energy can also fire this parallel burner.
Figure 1.10 shows the principle of a parabolic trough solar power plant.
In
solar thermal tower power plants
, hundreds, or even thousands, of large
two-axis tracked mirrors are installed around a tower (Figure 1.11). These
slightly curved mirrors are called heliostats. A computer is used to calculate
the ideal position for each of these and positioning motors ensure precise focus
on the top of the tower. The absorber is located at the focus of the mirrors on
top of the tower. The absorber will be heated to temperatures of typically
1000°C or more. Hot air or molten salt transports the heat from the absorber
to a steam generator where superheated steam is produced. This steam drives
a turbine and an electrical generator as described above for the trough power
plants. Demonstration plants exist in the US, Spain and Israel. Commercial
power plants are under construction in Spain.
Figure 1.11
Demonstration Solar Thermal Tower Power Plant in Spain
