Page 22 - Design of Solar Thermal Power Plants

1.2 BRIEF INTRODUCTION TO SOLAR THERMAL POWER GENERATION 15

1.2.1.3 Comparison of Solar Thermal Power and Solar
Photovoltaic Power Generation
1. Energy storage. Energy storage in CSP power generation has clear
advantages, in that thermal storage techniques are more mature
and much less expensive than other power storage techniques.
Currently, solar photovoltaic power plants are still unable to realize
the expectation of all-weather power generation, whereas CSP has
already accomplished this target. The remarkable feature of CSP
generation technology is the application of a thermal storage system,
which is also a major advantage of CSP generation versus
photovoltaic power generation. The thermal storage system
(Fig. 1.4) accumulates excess thermal output by the receiver under
intensive solar irradiation for use in case of clouds, overcast
conditions, and peak times while realizing: (1) generation capacity
buffering; (2) controllable power output; (3) stable power output; (4)
improvement in annual availability and the increment of full-
capacity generation hours; and (5) improvement in the effectiveness
of the CSP plant as well as a reduction in power generation cost.
Research has indicated that an CSP plant with a thermal storage
system can improve its annual availability from 25% (in the case of
no thermal storage) to 65%. Thus thermal storage technology serves
as a key factor in the competition between CSP generation and any
other renewable energy power generation. By applying a long-
duration thermal storage system, CSP generation is capable of
satisfying the requests of the basic load power market in the future.
Currently, the longest thermal storage time by a power plant has
exceeded 15 h.

FIGURE 1.4 Schematic diagram of thermal storage techniques in solar thermal power
generation.