Solar power: Solar thermal

In solar thermal power, sunlight is used as a source of heat that can be used to generate electricity. Usually the heat is used to turn water to steam which powers turbines, but this is not the only method.

	Photo: afloresm - Creative Commons 2007 Click to enlarge

A working example – the Solucar power plant, Seville, Spain. 

600 giant mirrors focus the sun's energy on to the top of a tower filled with water pipes. Amazingly, this power plant can even generate electricity at night. Find out how below

• Watch this BBC video about the Spanish solar power plant
• Or read more about it here: BBC article
• More photos
  

A disadvantage of this type of design is that it relies on mechanical systems to move the mirrors. At all times they must redirect the sun towards the tower. Such mechanical parts require maintenance and can fail.

	The thermal updraft tower - how it works. Click to enlarge.

A future example: the thermal updraft tower

This system has no moving parts except the turbine. Vast greenhouses collect hot air, which is funnelled up into an enormous tower. Inside the tower are fans that rotate and generate electricity as the hot air moves upwards.

A prototype of this system was built in Spain in the 1980's and the company behind it are hoping to build the actual full sized tower in the Australian deserts soon.
video clip            Wikipedia article

Photovoltaic power