Back in the 1970s, a German utility wanted to build a flexible storage plant
that could respond to sudden peaks in electricity demand, since its conventional plants — mainly coal — weren’t designed to dial up or down quickly.
It is the world’s first utility-scale concentrating solar power plant that uses extremely hot salt to extend the use of solar energy way past sundown.
Today, with the rise of green energy sources like solar
and wind, the need for industrial-scale energy storage is becoming ever more vital to make sure there’s power even after the sun sets or the breeze dies down.
The salt, which can stay liquid at higher temperatures than some other fluids like water, then flows through a steam-generating system
that drives a turbine, producing enough electricity for 75,000 homes for as long as 10 hours past sundown — in essence, allowing the sun to shine at night.
The plant, which opened in 1978, uses electricity from the grid, when it’s cheap because demand is low, to compress and store air in the salt caves.
A similar plant opened in 1991 in McIntosh, Ala. Several energy companies, mainly in the United States
and Europe, are exploring mining their salt deposits for storage as well.