Arizona is close to developing the first Concentrating Solar Power Tower

In Arizona, the first large-sized Solar Tower is about to be developed. The Southern California Public Power Authority (SCPPA) has approved the purchase agreement for power from the next-generation plant proposed by the Australian company EnviroMission, which the SCPPA had already approved in 2008.

The Solar Tower project represents a completely new approach to solar energy, compared with other solar technologies that are presently being used.

Indeed, it consists in an extremely high cylindrical tower built in the centre of a large area covered with solar collectors. The mechanism is based on a very simple concept: thanks to the collectors, the sun heats the water in a sort of “greenhouse” beneath the tower, causing the temperature to reach 70 °C, or more.

The heated air – which rises, according to one of the best known laws of physics – flows to the tower, forming a sort of hot draft that can power 32, 6.5 MW wind turbines.

Therefore, the facility will have a total capacity of about 200 MW and – according to its designer – a 50% capacity factor (meaning that the plant would be able to operate at a full capacity for 12 hours/day, also in cloudy days). Another advantage is that the Solar Tower does not use water.

The latter is significant, because its ideal location is in desert areas, where there is greater insulation and more land available for collectors (which cover a circular area of over 9 square kilometres). Also, if necessary, in these areas several bordering facilities could be built in order to reach a high capacity.

Under the project, a tower that is approximately 1,000 metres high and has a 130-metre diameter will be built. It will be the highest construction ever built by man, three times as high as the Eiffel Tower, by way of example.

A small-sized prototype (50 kW) has already been successfully developed in Manzanares, Spain. Also, a 200 MW project that uses the same technology employed in Arizona is being developed in Australia.