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Solar Chimney

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, coal 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.

Mildura Solar Tower

A solar tower, to be used as an alternative energy source under construction near Mildura, Australia, is set to be completed by late 2005 or early 2006.

The Solar Tower will be one kilometer high, becoming the world's tallest man-made structure, along with a base of 120 meters in diameter (the size of the Melbourne Cricket Ground's playing surface).

The idea was conceived by engineer-inventor Professor Jorg Schlaich, who built a 200 meter-tall prototype in Spain in 1983. The project, led by EnviroMission will contain thirty-two turbines, each of which will produce 6.25 MW, making for a 200 MW structure in all.

Besides providing energy for an estimated 200,000 homes, the Solar Tower will include an observation deck at the top, to increase tourism revenue. Also, new British technology has allowed for robot-assisted construction techniques for safe completion of the monumental structure.

EnviroMission claims the Tower will recoup the energy costs in its materials and construction in thirty months, and after that, it will make up for 700,000 tons of carbon dioxide which would be emitted from a coal-fired power station of equivalent energy output.

Citations:

http://www.enviromission.com.au/pdfs/ecos_sept_oct_2003.pdf

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