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 only one genuinely large-scale solar thermal plant – 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.

Construction is currently underway on the 44 MW Solar Boost project at Kogan Creek in Queensland. Scheduled to come online in 2015, the plant uses linear Fresnel technology and will be Australia's largest solar thermal power station when complete.

The future of solar thermal in Australia

Gigawatts of solar thermal energy have been installed around the world, and large-scale CST projects of up to 500 MW are being planned and constructed in countries such as Spain, Germany and the United States.

Australia's climate makes it an ideal candidate for large-scale CST generation, and declining costs will make the technology increasingly attractive. In 2012, the Australian Solar Institute predicted that solar thermal could make up between 30 and 50 per cent of Australia's power consumption by 2050.

In recent years, emerging renewable energy technologies such as solar thermal have been supported by the independent Australian Renewable Energy Agency (ARENA).  However, the Federal Government announced in May 2014 that ARENA would be abolished and its $1.3 billion of unspent funding removed. Without the support of ARENA, there is a risk that international CST investors will seek out other markets.

Sources:

  • Realising the Potential of Concentrating Solar Power in Australia report (Australian Solar Institute)
  • Clean Energy Australia Report 2013