The 19.9 MW Gemasolar plant can store heat energy generated throughout the day in two tanks of molten salt that combine 60% potassium nitrate and 40% sodium nitrate, and retain 99% of the heat for up to 24 hours. This stored energy can satisfy peak summer energy demand long after sunset.

This new technology has been adopted and commercialized so quickly it's hard to remember how novel it seemed just a year ago.
Nearby
, Andasol 1, built by Terresol in 2008, was the first CSP power plant in the world to use molten salt storage commercially - but for only seven hours a day.
Coming online just over a year ago, long before
BrightSource and
SolarReserve, the new $325 million Gemasolar uses 2,650 heliostats to

direct the sun's energy to heat molten salt in a receiver sitting on top of a 450 foot tall tower and is upending all assumptions of solar power's day-light dependence. A bit of global cognitive dissonance in spite of Torresol's 2010 award for "engineering firm of the year" and "commercialized technology Innovation of the year" at the
US CSP Today Awards.
Then late last June, Tony Seba, a US journalist traveled to see what was still considered