In Arizona A Solar Plant That Powers 70,000 Homes--Day or Night

"Outside Phoenix, Ariz., on Wednesday, a power company turned on one of the largest solar power plants of its kind in the world. But unlike other solar farms, this plant continues giving power to 70,000 Arizona households long after the sunset."

"The Solana plant uses 3,200 mirrors that are tilted so they focus the sun's rays to heat a specially-designed oil. That boils water, which drives turbines and generates electricity. Or, the oil can heat giant tanks of salt, which soak up the energy. When the sun goes down, or when households need more power, the hot salt tanks heat up the oil, which again boils water to drive the turbines."

"Whereas conventional solar panels only give power when the sun is up, these giant salt batteries give renewable energy on demand. They can store six hours-worth of energy, which can meet the demands of Arizona customers, according to months of test data."