Solar Chimney

A type of power stations based simply on the principle that warm air rises. Air underneath a glass ceiling is heated by solar radiation so that it rises through a chimney. To replace the air which has just risen, air from the edge of the glass ceiling flows inward, and will then itself begin to heat up. In this way the sun’s heat radiation is converted into kinetic energy, or a ‘motor’ of constantly rising air. A turbine built into the chimney then converts the wind power by means of a generator into electrical energy.

A solar flue is an air stream driven by temperature difference in a solar chimney power station. Solar chimney power stations are particularly suitable for generating electricity in deserts and sun-rich wasteland. Their efficiency increases with the height of the chimney, not linearly, but exponentially. For the power stations to generate electricity economically, not only large glass or plastic roof surfaces are necessary, but also a very high chimney. The height is needed simply from the fact that the updraft is proportional to the height, and also to make best use of the heat available. Even under very favourable conditions (global solar radiation of 2.5MWh/m²), a 5 MW power station needs a collector roof with 1100m of diameter; a chimney of 445m high and 27m in diameter. To produce 200 MW of power, a 5000m-diameter collector roof as well as a chimney of 1000 m in height and 150 m in diameters are needed