The best known solar tower using this technolgy was built as research in Manzanares area - Spain. To achieve this as a "light construction", materials and technologies coresponding to the 80' were used. The aim of the project was to produce a highly efficient energy system.
It has been estimated that this solar tower with a height of 550m, diameter of 45m and a collector diameter of 1.250m generates 5MW. The output power would be approx. 14 GWh/ year considering radiations about 2,300 kWh/(m2/year). The investment cost was evaluated at 42 mil Euro, of which 19 mil. Euro the tower, 10 mil Euro the collector and 8 mil. Euro the wind turbine, the rest representing other costs. In these circumstances, the cost of electricity would reach 0.21 Euro/ kWh considering an interest rate of 6% and a lifespan of 30 years. Even if the numbers are slightly optimistics, it appears that, in areas with solar potential, this type of application may become attractive in terms of technological progress - there are several attempts to achive such a construction in China (one tower made) and a project in Australia.
Based on these experiences and taking into account that most of costs (the tower and work related ) would be eliminated when using the chimney of the former coal-fired steam power plant CET II South Pitesti, a calculation was performed which revealed that the use of this chimney (height of 280 m) from the site, as a solar tower can be advantageous.
The proposed solar tower using the existing chimney is shown in Figure No. 2
The estimated economic calculations, the amount required for equipping the solar tower is approx. 200.000 Euro (of which 120.000 Euro wind turbine;60.000 Euro collector; 20.000 other costs of adaption to the chimney).
The assembling of wind turbine with multipol electric generator at the base of the chimney is shown above; .
The calculation scenario for solar tower with updraft air flow has been one moderate in which we considered an average solar radiation of approx. 500 W / m2; location according to European solar map *3+ (July for example).
Solar tower - solar chimney - consists in an aplication that works due to thermal pressure caused by the variation of air density under the effect of changing temperature between the input at the base of the tower and the output section.
The air speed can be increased by placing a wind turbine at the base obtaining electricity proportional to the rotor operating parameters and the air state parameters.
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