California Power Grid Strained By Heat Wave

SOUTH SAN FRANCISCO, CA - AUGUST 30: Towers carrying electical lines are shown August 30, 2007 in South San Francisco, California. With temperatures over 100 degrees in many parts of the state, the California Independent System Operator, which manages most of the California electricity grid, is planning on declaring a minor power emergency later in the day, followed by a Stage 2 power alert during the late afternoon, indicating that power reserves have fallen below five percent. (Photo by Justin Sullivan/Getty Images)