Concentrated solar thermal (CST) technology harnesses the sun's power to generate electricity. It uses lenses and reflectors to concentrate sunlight, heating a fluid such as water or oil and producing steam to drive a turbine.

The advantage of concentrated solar thermal technologies is that they provide a dispatchable energy supply – that is, their power output can be adjusted based on grid demand. This makes them more flexible than traditional solar PV plants.

Globally, solar thermal technology is being deployed on a large scale to provide electricity, and storage systems are also being investigated.

Abundant sunshine and plenty of open space means Australia is ideally placed to take advantage of solar thermal technologies for energy generation.

Types of concentrated solar thermal technology

There are several types of CST plants:

  • Linear Fresnel – consists of long rows of flat or slightly curved mirrors that move independently on one axis. The mirrors reflect sun to fixed linear receivers mounted above them on towers.
  • Tower – involves an array of heliostats (large mirrors with two-axis tracking) that concentrate sunlight onto a fixed receiver at the top of a tower.
  • Dish – a highly efficient emerging technology in which a paraboloidal dish with two-axis tracking focuses sunlight to a point receiver.
  • Trough – the most widely deployed technology. Uses parabolic mirrors to track the sun from east to west.

Concentrated solar thermal in Australia

CST energy generation in Australia is still in its early stages of development. This is primarily due to the relatively high cost of the technology compared to more established forms of renewable energy.

Australia currently has two large-scale solar thermal plants – a 44 MW plant at Kogan Creek in Queensland which uses linear Fresnel technology and a 9.3 MW facility that has been added to the Liddell coal-fired power plant in NSW. Covering some 18,490 square meters, the linear Fresnel array is used to pre-heat feedwater for the coal-fired power station.

The future of solar thermal in Australia

Construction on a 150 MW concentrated solar thermal plant is scheduled to begin in South Australia in 2018. The Aurora Solar Energy Project will use heliostats to concentrate sunlight onto a tower that heats molten salt, which is then used to create steam to run turbines that generate electricity.

The project, which will be the largest of its kind in the world upon completion, will store energy for up to 10 hours and has the distinct advantage of being able to provide dispatchable power at night or on days with low wind.

Australia's climate makes it an ideal candidate for large-scale CST generation, and the Aurora Solar Energy Project will give the sector a considerable boost.

Sources:

  • Realising the Potential of Concentrating Solar Power in Australia report (Australian Solar Institute)
  • Clean Energy Australia Report 2018