Solar Thermal Power Plants - Renewable Energy: Technology, Economics and Environment - page 192

Normal operation. As for all thermal power plants also solar thermal power plants
have certain environmental effects during normal operation. In the following,
selected aspects are discussed.
- Land requirements. Solar thermal power plants use solar radiation as a source
of energy, i.e. an energy source with a comparatively low energy density. This
is why such plants necessarily require large collector areas and thus extensive
land areas (Table 5.5). Since the individual collectors must be accessible during
operation, the soil, where the collector field is installed, is compacted and lev-
elled during construction. Furthermore, highly grown plants may disturb opera-
tion and reduce the technical lifetime of the collectors (due to e.g. humidity,
shading, and fire hazard). Thus, at the most, grass vegetation is permitted on
the respective terrain of e.g. a solar thermal power plant). The soil is therefore
more susceptible to erosions. Since solar thermal plants are generally located in
areas with little precipitation (i.e. deserts and steppes) and collector fields must
be provided with extensive drainage systems to protect foundations and ensure
accessibility, this influence can almost be neglected. Due to the glass reflectors,
the collector fields are susceptible to damages caused by e.g. extreme winds.
The entire plant is thus generally fenced in, so that during the construction of
such a solar thermal power plant it has to be ensured that neither natural habi-
tats of large animals nor typical passages are affected. However, due to the pre-
ferred location in desert or steppe areas this requirement can generally be ful-
filled without any problem.
Table 5.5 Space requirements of solar thermal plants

20 - 35 m 2 /kW

Tower power plants

10 - 25 m 2 /kW Line-focussing power plants

15 - 30 m 2 /kW

Parabolic trough power plant

approximately 200 m 2 /kW Solar updraft tower power plant

approximately 55 m 2 /kW Solar pond power plant

- Visual impact. Due to their central tower, mainly tower and solar updraft power
plants have a non-negligible impact on the appearance of the natural scenery;
and the higher the tower the bigger this influence is (approximately 100 m in
case of solar tower power plants, and 1,000 m for solar updraft tower power
plants). Contrary to wind energy converters, the disturbance of the scenery is
static since no moving parts (such as the rotors of wind energy converters) are
involved. This is why the impact on the natural scenery is more readily ac-
cepted by the spectator. Furthermore, the visual impact can be limited by corre-
sponding shapes and colours as it is presently the case for wind energy con-
verters. At night time, indispensable aviation warning lamps might be per-
ceived as disturbing. Since the tower height amounts to 15 to 25 % of the col-
lector field radius, disturbing shading outside of the plant only occurs with
solar altitudes below 15°. Since such plants are preferably built in desert or