Hot (pun intended) on the heels of the building of the world’s largest battery, the state of South Australia has now granted approval for the construction of a huge thermal solar generating station, the ‘largest of its kind’ on the world.
The Aurora Solar Energy Project integrates solar thermal technology with molten salt energy storage to create an electricity generating station more like a fossil fuel or nuclear facility than we usually think of when the word solar is involved.
Coal, natural gas, biomass and nuclear generating stations all operate by using the fuel to boil water to drive a steam driven turbine. A solar thermal generator simply uses the energy of the sun to boil the water.
The sun heats salt, which heats water and is also used as a storage ‘battery’ for the heat sun so that the facility can operate when the sun goes down.
Here’s how it works:
There are 12,000 ‘heliostats’ or movable mirrors, that track the sun’s rays and focus the light and heat on a tall concrete tower, or receiver.
Inside the receiver is cold molten salt. By ‘cold’ we mean 288 degrees Celsius, or 550˚ Fahrenheit.(continued below image)
As it goes through the receiver the salt gets about twice as hot: 566˚C (1050˚F) and is then pumped to the hot salt storage tank.
The hot salt is pumped, as needed, through a steam generator to produce steam that in turn drives the turbine to generate the electricity.
The salt is now cold again from having boiled the water, and gets pumped back up the receiver to start all over again.
This Aurora facility has a massive 1,100 megawatt-hours of molten salt storage that can provide 8 hours of full load power after dark. This means that, from storage (its ‘salt battery’) alone, Aurora will be capable of powering the equivalent of over 230,000 homes for 8 hours, or around 35% of all of the households in South Australia.
One of the advantages of fossil fuel generators is that they can be quickly ramped up to meet short term high electricity demand. The huge hot salt storage capacity of this system, which doesn’t always have to be used, allows for the same quick reaction. More more molten salt can be sent to the steam generator as necessary without any emissions.
The other aspect of a solar thermal power station that is different from photovoltaic solar farms is that many of the jobs require the same skill sets as conventional energy jobs – from construction phase through to operations.
This megaproject is anticipated to create 4,000 direct, indirect and induced jobs during construction (which includes 650 full time construction jobs) plus 50 full-time permanent jobs for operations and maintenance.
The Aurora facility is being built by SolarReserve, a US-based company which was founded in 2008 and has now assembled a pipeline of over 13 gigawatts in 20 countries.