Harnessing direct solar energy – a progress report
Box 4 | The Big Dish
Photovoltaic cells aren’t the only way of converting sunlight to electricity. The Big Dish, at the Australian National University’s Solar Thermal Energy Research Centre in Canberra, does it another way.
As its name implies, this solar collector is shaped like a satellite receiving dish. It is actually a solar thermal generator because it relies on heat. The huge curved mirror – the dish – focuses sunlight onto a central container where water is super-heated to steam at a temperature of 1500°C. If you’ve seen how steam at 100°C will escape from a kettle, you’ll appreciate how a much higher temperature could cause even a small amount of steam to expand with massive pressure. This can be used to do work – in this case driving a special generator that produces electricity.
The dish is steerable, so it can track the sun across the sky. Because it is always facing towards the sun, it gathers the maximum amount of energy. The dish isn’t just used for experimentation – it pumps 80 kilowatts of electricity into the Australian Capital Territory’s grid.
With the success of the Big Dish, and using the know-how of the project’s director Professor Stephen Kaneff and his team at the Australian National University, plans are underway to set up a working demonstration plant to provide a hefty 2 megawatts of electricity for Tennant Creek, in the Northern Territory.
Boxes
Box 1. Eliminating the zeroes
Box 2. Driving on a sunbeam
Box 3. Light to electricity
Box 5. Chemical fuels from the sun
Related sites
Solar Thermal energy research (Australian National University)
Solar thermal – technology status overview (Australian Government Department of the Environment and Water Resources)
Page updated January 2010.