Page 26 - Design of Solar Thermal Power Plants

1.2 BRIEF INTRODUCTION TO SOLAR THERMAL POWER GENERATION 19

FIGURE 1.8 Solar tower power generation of Gemasolar plant owned by Torresol
Energy, Spain. Picture provided by SENER, Spain, 2018.
receiver. The concentration ratio of solar tower power generation falls
into the range of 300e1000, and thus it is easy to realize a comparatively
higher system operation temperature. Furthermore, solar tower power
generation systems feature a short heat transfer path, small heat losses,
and high collection efficiency. Therefore, the solar tower power generation
system features comparatively higher comprehensive opticalepower
conversion efficiency.
Based on different thermal transfer media in the receiver, the system
operational mode and performance characteristics of the power plant
may be distinguished from each other. Thermal transfer media that are
currently available mainly include water/steam, molten salt, and air. In a
water/steam power plant system, high-temperature high-pressure steam
generated by the receiver can be directly used to drive the steam turbine
to generate power; it enjoys the advantage of a thermal-absorbing me-
dium that is the same as the working medium, and annual mean effi-
ciency can exceed 15%. A molten-salt power plant system uses an indirect
thermal cycle power generation system, which requires the use of a
molten-salt/steam generator to indirectly produce high-temperature
high-pressure steam to drive the steam turbine to generate power.
Compared with the water/steam power plant system, a molten-salt sys-
tem can realize supercritical, ultrasupercritical, and other high-parameter
operational modes due to low pipeline pressure during high-temperature
operation and thus further improve the efficiency of the solar tower
thermal power generation system. It is also convenient for storing energy