Solar hot air

Solar hot air

Solar gas turbine - Brayton cycle

The CSIRO in Newcastle have a solar heated gas turbine. Mirrors reflect sunlight onto the chamber, heat the air and expand it.

On cloudy days or at night they use methane. It looks very promising.


The SunCatcher solar thermal system runs a Stirling engine. Each 12M diameter dish generates 25 kilowatts.

The project had not gone ahead by 2012 due many factors. More.

Alpha type Stirling engine.

There are two cylinders. The expansion cylinder (red) is maintained at a high temperature while the compression cylinder (blue) is cooled. The passage between the two cylinders contains the regenerator.


Beta Type Stirling Engine.

There is only one cylinder, hot at one end and cold at the other. A loose fitting displacer shunts the air between the hot and cold ends of the cylinder. A power piston at the end of the cylinder drives the flywheel.

Solar updraught tower

An updraught is simply a very tall chimney, about 800 M. The area surrounding the base is transparent so the air is heated. As it rises up through the stack, it rushes past turbines, generating electricity. 

There are several advantages:

  • Due to the soil under the collector working as a natural heat storage system, Solar Updraft Towers can operate 24/7 on pure solar energy.
  • No cooling water is needed as for many other solar thermal power plants.
  • Solar updraft towers are particularly reliable. Turbines and generators -subject to a steady flow of air -are the plant's only moving parts.


Hyperion is planning one in West Australia to supply power to the mines in the area.

The tower will be the tallest building in the world at 1 KM high and 120 M diameter.

The glass house will cover 3,600 Ha and the film will be 1 mm thick. 36 turbines will capture the air's movement as it rushes up the tower.




he site chosen has plenty of sun with stable weather.

Solar downdraught tower

This is the reverse of the updraught tower. The hot air is cooled and made denser by spaying water into the air at the top of the tower. The sinking air reaches speeds in excess of 80 kph and passes through turbines at the bottom.

Vertical wind vanes would also capture any prevailing wind for extra energy.

The site would need hot dry air and a water supply.



Clean Wind Energy Co.

Clean  Technica