Solar Thermal Power Plants - Renewable Energy: Technology, Economics and Environment - page 202

ence site power generation costs are calculated with 0.12 €/kWh for the parabolic
trough power plant with integrated thermal energy storage (Table 5.9).

Table 5.9 Estimation of the power generation costs of a parabolic trough power plant with
thermal molten salt storage
Nominal capacity

50 MW

Investment costs a 260 Mio. € a

Operation and maintenance costs 5.1 Mio. €/a

Electricity generation costs 0.12 €/kWh

a including storage.

As for solar tower power plants, not only the full-load hours and the assumed
mean interest rate can influence the power generation costs significantly. There-
fore a sensitivity analysis is conducted on the basis of these and other parameters.
The result of such an analysis show very similar correlations as for the reference
solar tower power plant (Fig. 5.13). Accordingly different electricity generation
costs are obtained depending on the economic frame conditions and/or the as-
sumed technical parameters.

Environmental analysis. The environmental effects of parabolic trough power
plants are very similar to those of solar tower power plants. They are thus dis-
cussed in the corresponding chapter on solar tower power plants (see Chapter
5.2.2).

5.4 Dish/Stirling systems

Dish/Stirling systems mainly consist of the parabolically shaped concentrator
(dish), a solar receiver and a Stirling motor as thermal engine with interconnected
generator.
The parabolic concentrator is tracking the sun in two axes, so that it reflects the
direct solar radiation onto a receiver positioned in the focus of the concentrator.
The radiation energy transformed into heat within the receiver is transferred to the
Stirling motor, which, being a thermal engine, converts the thermal energy into
mechanical energy. A generator is directly coupled to the Stirling motor shaft,
which converts the mechanical energy into the desired electrical energy
(Fig. 5.20). For hybrid operation, the system may be heated in parallel or in addi-
tion by a gas burner (operating e.g. by natural gas or biogas).
In the following, the main components of such systems are discussed. Subse-
quently, the corresponding complete systems are assessed.