Encyclopedia of Environmental Science and Engineering, Volume I and II

ENERGY SOURCES—ALTERNATIVES 313

described in the following as a example of a solar power

plant. In this CRS (Central Receiver System) tower concept,

heliostats reflect all incident radiation to a central receiver

at the top of a tower. Within this receiver, temperatures

ranging from 500 to 1000°C can be obtained. Table 15 lists

the tower plants constructed up to now, of which solar 1 in

Barstow in California, USA, Table 16, is the largest at 10

MW. For some 10 years, such prototype power plants have

been designed, constructed and tested in different parts of

the world. In their key characteristics, such as technology,

conceptual design, size, heat carrying medium and power

may differ from each other. For the tower power may differ

from each other. For the tower power plants Solar 1 (Barstow,

USA), CESA 1 (Almeria, Spain), Sunshine (Nio, Japan) and

Eurelios (Adrano, Italy), steam was employed as the heat-

carrying medium. The SSPS plant in Almeria, Spain, was

operated with liquid sodium; the French power plant Themis

used a molten salt for this purpose.

Since the beginning of 1987, the plants have been brought

together under one organization under the leadership of

Spain to make up the “Platform Solar de Almeria” (PSA) and

now represent the European centre for solar thermal energy

research.

Research work in the future will result from consultations

between West Germany and Spain, as well as the participation

of other nations in the SSPS project (participants: Switzerland,

West Germany, United Kingdom, Italy, Sweden, USA). The

activities are directed to the three following areas:

• maintenance and upgrading of the plants


• high-temperature technology of the components (in
  particular concentrator, receiver, storage device)


• utilization of the radiation and thermal energy
  during endothermic reactions in chemical pro-
  cesses for the production of transportable fuels
  and chemicals

In the farm concept, which is under investigation not only

in Almeria but also in the USA and Australia, solar radia-

tion is focused by parabolic troughs onto pipelines under

glass functioning as receivers. The maximum temperatures

attainable with such systems are in the range 300 to 400°C

depending on the oils used as heat-transfer media.

Direct conversion of solar energy into electrical energy is,

environmentally, the most acceptable way of electrical power

generation. Solar cells are already supplying spaceships with

electrical energy. For the construction of solar power plants,

concept and feasibility studies are in hand. Even if electricity

generation in this type of plant does not fulfill conventional

ideas of “profitability” great importance must be attached

to attempts to introduce environmentally-neutral systems

of power generation into the world. These endeavours are

Heliostats

Transformer

Steam Turbine

Steam Generator

Heat Storage Tanks

Generator

Receiver

FIGURE 5 General arrangement of Central Receiver Systems (CRS).

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