Environmental Engineering Reference
In-Depth Information
and photovoltaic plants. As a result, the operation of solar thermal power plants is
less feasible for economic reasons (Figure 7.15).
Figure 7.15
In sunny regions solar thermal power plants (right) can currently produce electricity more
cheaply than photovoltaic power plants (left).
In Spain, the cost of generating electricity from parabolic trough and solar tower
power plants in 2008 amounted to about 20 cents per kilowatt hour; at top locations
in North Africa the cost was about 15 cents per kilowatt hour. So, although these
power plants are less expensive than those using photovoltaics, they are consider-
ably more expensive than conventional fossil or nuclear plants. As with photovolta-
ics, costs are expected to fall considerably when these plants start to be built on a
large scale. Costs are already dropping fast as a result of the many new solar trough
and tower plants being built. Within a decade solar thermal power plants could
already be more economical than conventional plants.
In the case of solar chimney and Dish-Stirling power plants, there are no signs yet
of a comparable rapid market development. Different studies show that these plants
also have the potential in the long term to be competitive in electricity generation.
It is also calculated that concentrating photovoltaics plants will be able to generate
electricity at a lower cost than normal photovoltaic plants in locations with high
solar irradiation. Various suppliers have developed interesting systems over the past
few years, but concentrating systems still have to prove their viability.
The advantage of photovoltaic systems compared to solar thermal systems is modu-
larity. Photovoltaic systems can be built in any size wanted - ranging from milli-
watts all the way to multi-megawatt plants several square kilometres in area. Solar
thermal power plants are always dictated by the minimum output that is needed to
make the plant economically viable. With Dish-Stirling power plants, this is around
