Theoretical area needed for solar-thermal plants in the Sahara
The enormous solar radiation potential makes solar-thermal power generation in desert regions extremely interesting. Dr. Gerhard Knies (founder and Chairman of the Board of Trustees of the Desertec Foundation) estimated the potential of the deserts to be so high that more energy was received from the sun in six hours than humankind consumes in one year.
On average, the energy of solar radiation in North Africa amounts to around 2,200 kWh per square metre, or 2.2 TWh per km² per year. Assuming an efficiency rate of about 10%1, a square surface of 300 x 300 km would theoretically be sufficient to cover global electricity needs of 20,000 TWh2. To meet power needs in Germany, some 527 TWh (20123), a surface of 2,400 km² would theoretically suffice. That’s about equivalent to the size of Luxemburg, or a square sized 50 x 50 km.
In practice, however, when planning a solar-thermal plant many factors must be considered before a suitable site is found. On the one hand, the gigantic mirrored surfaces must be installed on extremely even ground. And on the other, water is needed for cleaning the mirrors and for cooling. There also must be sufficient space between the rows of mirrors for cleaning vehicles and maintenance work. The areas available for constructing a power plant with a capacity of several hundred megawatts (MW) are limited, even in the desert. For this reason, separate plants with a capacity for 100 to 500 MW will initially be built.
1 Takes into account the ground area needed for the plant, but not topographical restrictions, e.g. slopes. Power losses through a distribution grid are likewise not taken into account.
2 Source: rough estimate by the International Energy Agency
3 Source: BDEW