Storing sunlight in salts

Originally Published in Engineers Australia Magazine - Power Engineering Section Page 58 Using molten salt to store solar energy could provide electricity 24 hours a day, equivalent to baseload supply, according to Matthew Wright, executive director of Melbourne based company Beyond Zero Emissions.

"There are plants in Spain operating with energy storage right now, providing electricity all night long," Wright said.  Molten salt storage uses common salts, such as potassium nitrate, which are readily available and non-toxic.  Using the sun's energy, these salts are heated to high temperatures and stored in insulated storage tanks.   When electricity is needed, the heat in the molten salt is used to create steam to drive a turbine.

According to the company, this sort of electricity is dispatchable, meaning it can be sent out on demand at any time of day, so it can replace the baseload electricity generated from burning fossil fuels.

"Solar thermal power with storage is proven technology, which will reliably provide the backbone of modern renewable electricity grids," Wright said.

"The EU has been investing in the solar thermal storage power sector for more than a decade.  The US, Middle East and North Africa have proposals in the pipeline that, combined are five tiimes greater than Australia's total coal-fired electricity capacity.  Spain has 15,500MW of solar thermal plants approved through the planning process, more than enough to power all of NSW, and 34 massive power plants are under construction right now."

Wright argued Australia should follow the example set by the Spanish government which supports solar thermal power with a feed-in tariff for large-scale solar installations.

"Australia is the country with one of the best solar resources in the world.  We have some of the best researchers in this area too.  Despite this, the federal government remains in thrall to the coal lobby, investing in dead-end fantasties like carbon capture and storage, while other countries develop their solar thermal expertise and manufacturing.

"Solar thermal power with storage will soon be cheaper than new coal-fired powerstations according to US Department of Energy projections.  Unfortunately the Federal Solar Flashships Program is skewed to favour 1980s style daytime-only solar plants rather than the newer standard of baseload solar thermal storage plants that are being built now in Europe and the US," he said