Solar Thermal Power Plants - Renewable Energy: Technology, Economics and Environment - page 188

In principle, this concept allows to generate power not only at daytime but also
during the entire course of the day provided that the energy storage and the solar
field are sufficiently large. Solar Two shows an electric output of 10 MW which
can be maintained up to three hours after sunset thanks to the plant's energy stor-
age.

Phoebus/TSA/Solair. Phoebus/TSA/Solair is a power plant concept with an open
volumetric air receiver that provides hot air /5-8/. The hot air is subsequently
passed through a steam generator providing superheated steam that can be used to
drive a turbine/generator unit. Fig. 5.12 shows the corresponding schematic dia-
gram.

Air receiver

700 °C

Generator

Turbine

G

Duct burner

Direct
solar radiation

Steam
generator

Fan

200 °C

Condenser

Fig. 5.12 Schematic diagram of an open volumetric air receiver according to the Phoebus-
principle equipped with duct burner for additional fossil fuel firing (see /5-12/)

A natural gas-fired duct burner placed in between the receiver and the steam
generator adds heat to the air if solar radiation is insufficient to supply the desired
steam quantity. The Phoebus plant can thus not only generate power in times of
sunshine but also during spells of bad weather and during the night; power gen-
eration is thus not exclusively dependent on the available solar radiation.
From 1993 to 1997 such a cycle equipped with an air receiver and a thermal
capacity of 3 MW was continuously operated, containing all components of a
future Phoebus power plant (so-called TSA system (Technology Program Solar
Air Receiver)). Test results have shown the good interaction of components and
the low thermal inertia of such systems which enable fast start-up. Further benefits
of this technological approach are a simple structure and the unproblematic heat
transfer fluid air /5-13/.

PS10. Because of the good experience made with the Phoebus/TSA/Solair System
a European consortium, led by a Spanish company, planned the construction and
operation of a 10 MW plant named PS 10, equipped with a volumetric air re-
ceiver, in the Southwest of Spain in 2004 /5-14/. However, the concept has been