Electricity generation
Two methods have been proposed as the most promising. For terrestrial use in certain areas, the solar furnace is the most likely to be investigated. A typical installation would consist of rows of parabolic reflectors. Situated at the focus of each reflector would be a pipe carrying a heat-exchanger medium (possibly liquid sodium). The solar energy absorbed by the fluid could be used to raise steam for a conventional plant.
The solar furnace would be most practical in desert regions, but again they are at present economically unrealisable. It is difficult to pipe in water for steam raising and condenser cooling. Also the hostile climate (hot days and cold nights) could cause very high thermal stress in overhead transmission plant. Only in a land reclamation scheme where desert areas are made fertile would such a scheme be considered economic. As a point of interest, a solar furnace at the Pic du Midi observatory in the French Pyrenees has obtained temperatures approaching 6 X 103 °C at the focus.
The second method is by means of a geostationary Earth satellite with several square kilometres of solar arrays. The power would be transmitted down as a narrow beam of microwave power to a large dish antenna. The popular fears of a path of destruction should the satellite drift off station are unfounded. The slant angle of the beam would cause such a wide area to be 'illuminated' that the heating effect would be very small indeed.