With scorching temperatures across the country, millions of American home and business owners are running their air conditioners full bore. Utilities have strained to meet the surge in demand for electricity. Outages have occurred here and there, particularly in the densely populated Northeast. But for the most part, demand has been met. Some utility executives credit a government-encouraged program called demand-response. It rewards customers for reducing power usage at peak times. We discuss the merits and pitfalls of the program and other efforts to manage the nation's power grid.