A (Load) Balancing Act: The Challenge Of Clean Power : NPR

Solar and wind power are booming in California, but there are times when the sun doesn't shine and the wind doesn't blow. So California utilities are looking to smooth out those bumps by doing something rarely done on the grid today: storing electricity."

The California Independent System Operator is the traffic cop of the state's electrical grid. Its job is to forecast how much electricity the state needs — every four seconds — and to make sure it's supplied. Inside an unmarked building outside of Sacramento, dozens of people are glued to computer screens, and on one wall, there's a display plotting a big red line showing how much electricity California is using right now, in real time.