A Solar Thermal Tower runs on the thermal law that hot air rises. Basically the way a thermal tower works is very similar to what would happen if you combined a convection oven with a chimney.
A solar thermal tower has three main parts. The tower, the collector, and the turbine. The more prominent is the tower itself. The tower is almost like an exhaust. Around the tower is a huge collection area. The collection area is usually a covering of very thin film polymer sheeting, glass, plexiglass or lexan. The sun hits the collection material, heating the area underneath. As this air gets warm up to around 100 deg, the air looks for an escape route. The heated air can reach speeds of up to 35 mph when exiting out of the thermal tower. If you put wind turbines inside the tower so that the heated, escaping air is making them spin, the heated air can be used to generate electricity.
This type of power plant also works at night. With no modification, the sun not only heats up the air in the collector area, but it also heats up the ground, so at night when the sun goes down, the ground releases its heat which still produces the air current to make the turbines generate electricity. Because of the obvious absence of heat, the power output will not be quite as much as during daylight hours. However if water is piped through the collection area, it will hold and transfer more heat with greater efficiency when the sun goes down.
One of the main drawbacks to this type of power generation is the need for size. The more area for collection, the greater the amount of heated air, the more power is generated. The same adjustments in output are made with the change in tower height and diameter. The more air you can heat and push through the chimney, the faster you can spin turbines and the more power the can generate. This means more land will be needed and taller stacks. The best types of land for these power centers seem to be desert or otherwise lower valued land.
Source by Michael Motley