World’s largest solar thermal plant to be built in South Australia

The Government of South Australia announced today that the world's largest solar thermal plant will be built in Port Augusta.

An artist's impression of the solar thermal plant to be built in SA. Image courtesy of Solar Reserve.
An artist’s impression of the solar thermal plant to be built in SA. Image courtesy of Solar Reserve.

The plant, which will be constructed and run by Solar Reserve, won a competitive tender for the contract against a number of different proposals including more tradition coal plants.

As part of this, Aurora Solar Energy has secured a 20-year contract to provide South Australia with solar energy, at $78 per megawatt-hour a price reportedly lower than any competing company.

Construction is expected to begin next year, and the plant will be up and running by 2020.

Once fully operational the solar plant will be able to produce 150-megawatts of energy, comparable to the amount of power used by 90,000 homes, or approximately 5% of the state’s energy requirements.

The plant will reportedly cost $A650mn to build with a $A110mn loan from the federal government covering some of this cost.

“We are supporting this nation-leading renewable energy project because it will deliver more competition into our energy market and put downward pressure on power prices for households and businesses,” said South Australian Premier Jay Weatherill.

Solar thermal – a baseload alternative?

Unlike solar photovoltaic plants which convert sunlight directly into electricity, solar thermal plants convert sunlight first to heat.

In most designs, including the one proposed for Port Augusta, a central tower is surrounded by a field of sun-tracking mirrors called heliostats. These heliostats concentrate the sun’s light and heat onto the top of the tower, heating a column of molten salt.

This molten salt is then used to heat steam which drives a traditional turbine, and in doing so, generates electricity. The advantage of this kind of system is that it can store the hot, molten salt in tanks through the night, and slowly use this stored heat to generate power even when the sun isn’t shining.

In the case of the Port Augusta plant, it will be able to generate electricity for up to eight hours without sunlight, and thus provide consistent baseload power for the state.

Given that the technology is also relatively cheap to build, it suggests that this kind of approach could see considerable proliferation – especially in sunny areas – as it can provide an alternative to polluting coal plants.