Concentrating Solar Power

As all children soon discover, a magnifying glass can concentrate sunlight in one spot to set a piece of paper on fire. This simple example of concentrating solar energy can be applied on an industrial scale with the use of parabolic-shaped mirrors. Sunlight is reflected by the mirrors and converges in the so called focal point: Concentrating Solar Power (CSP). A liquid running through a tube located in this point will be heated. The obtained energy is used to heat water and convert this water into steam. The steam makes a turbine run which drives a generator that produces electricity (figure 1.a). The amount of electricity that can be produced by a CSP-plant depends on the intensity of the incoming sunlight, the surface of the mirrors and the efficiency of the plant.

A CSP-plant can be equipped with thermal energy storage capacity to allow storage of redundant energy during the day. This technology stores the surplus of energy in melted salt allowing continued electricity production during the night. CSP is an environmental-friendly technology with no harmful emissions or waste products reducing man’s footprint on the natural environment. All necessary materials (glass, steel, mirrors) that are required for the construction of such a plant are amply available.

The idea of Concentrated Solar Power is not new. On the contrary, in 1870 the Swedish born engineer John Ericsson built the first solar-powered steam engine based on this concept. In the 1980s, nine commercially operated CSP-plants were built in California with a cumulative capacity of 354 MW, supplying the southwest of the United States every year with approximately 800 million kilowatt-hours (kWh), enough for more than 200,000 households.

Since CSP-plants depend on the amount of incoming solar energy, obvious locations for the construction of such a plant are Africa, parts of South America, Middle East, southwest of the United States, Australia and Southern Europe (figure 1.b). On the African continent, Algeria, Libya, Egypt, Niger, Chad, Sudan, Botswana, Namibia, Angola and Zambia seem to be the most qualifying countries based on the amount of incoming solar energy.