What is a Solar Tower
A Solar Tower uses the power of the sun and the fact that heat rises to generate zero emission electricity. Sunlight heats the air at the base of very tall tower which then rises and turns an electricity generating turbine. With a very tall tower the updraft effect sucks the heated air even more rapidly upwards increasing the amount of electricity which can be generated.
At ground level a wide air-tight transparent collector is constructed covering a wide area of land to capture as much of the sun’s energy as possible using the greenhouse effect. The air in the collector heats up and rises up through the tall chimney built in its centre turning the turbines located near the base of the chimney. The collector stays warm throughout the night enabling significant amounts of electricity to be generated even when it is dark.
Air at 30 degrees Celcius at the edge of the collector is heated up to around 70 degrees Celcius at the centre. The temperature differential between the top and bottom of the tower results in an updraft velocity of around 15 metres per second which means that maintenance crews can do their work without requiring generator down time.
Solar Tower Prototype
A 50kW prototype solar tower (pictured above) was constructed in Spain way back in 1982. This plant 150km south of Madrid had an 800 foot diameter collector and a 600 foot tall 33 foot wide tower. Over the next seven years the solar tower operated for 15,000 hours during which time enormous amounts of tests were undertaken. It proved possible to run the power plant automatically with just one supervisor required, and the concept was proven to be a very reliable means of generating clean electricity.
It was also found that by using heat storage units within the collector space, it is possible to store energy so that electricity can be generated during peak demand – an advantage over traditional photovoltaic solar panel electricity generation. Shutter doors at the top of the collector can be opened and closed automatically to keep or release the stored heat energy. The ground under the glass collector is covered with a heat absorbent membrane to help store energy and make 24-hour operation possible.
200MW Solar Tower Project
Results from the prototype solar tower, wind tunnels, and other testing have proved that it is possible to scale up and build far larger solar towers. It has been shown that it is much more efficient to build one massive solar collector and tower rather than many smaller ones. Therefore the $800 million Australian project will have a 1,000 metre tall , 150 metre diameter tower making it easily the tallest man made structure in the world. The tower is a simple high tensile reinforced concrete structure which will last at least 50 years in the dry climate of Australia.
The collector for the 200MW solar tower will be vast with a diameter of approximately five kilometres. The height of the transparent roof of the collector will increase from a minimum of a few metres to much higher toward the base of the tower to direct the heated air up the vertical tower. The material used for the 24 million square metre collector could be glass, poly-carbonate, or plastic film.
Construction will take almost three years with the giant solar tower being built on the border of Victoria and New South Wales in the South East corner of Australia. Almost 3,000 construction workers will be involved in building the power plant with just 15 employees required to supervise, run, and maintain the completed site.
The solar tower will reduce carbon dioxide emissions by almost 1 million tonnes per year compared to a 200MW brown-coal powered generator.
More Information about the 200MW Solar Tower
To find out more about the 200MW Solar Tower project click here to view the SolarMission website.