The principle behind a solar chimney is quite simple and it is not all that different from the idea of having a hydroelectric dam. Firstly, a large glass roof is put up over a large area (the bigger the better) with a roof that slopes slightly upwards towards the centre. In the centre is a large "chimney" that (will work best when it is high) between the glass floor and the chimney is a collection of wind turbines facing inwards. During the day, as the sun shines down on the ground (as it can pass through the glass) the air begins to rise. As it does so the air is channeled into the centre by the sloping roof, where it will be pushed up through the chimney and out the top, spinning the generators as it does so. Water pipes are placed beneath the glass on the floor so that they are heated during the day and release their heat at night.
This method is more efficient than solar power as not only can it produce 24-hour a day power, but it will also keep operating if there is no sun (though obviously it will work better on a sunny day) because it can utilise all types of solar radiation
, allowing use in overcast climates. Also this method of power production requires very little maintainance because the only moving parts are the generators
. No cooling water is needed, so they can be used in very hot climates. Although solar chimneys do not provide the huge amount of power that heat (nuclear
etc) power stations can provide, they are much cheaper in the long term and they have no environmental side affects, apart from their aesthetics
200MW Mildura solar chimney
Already this technology is being put to use in australia, where a solar chimney 1000m high is being constructed. This will be able to produce 500GW hours per year. It is due for completion in 2005.