the time. And they produce the lowest-cost energy. About 7:00 o'clock, our load will start to pick up as people get up and go to work, and buildings start opening up and air conditioners go on. What we'll do is turn on different generating plants as demand increases. NARRATOR: All over America, the scene is the same. As the day gets going, the demand for energy ramps up. And since most of this energy comes from fossil fuel, it all adds greenhouse gases to the atmosphere. Take the simple act of making toast. Over the course of a year, a toaster on average consumes about 39 kilowatt hours of electricity. And each one of those kilowatt hours sends about half a pound of carbon into the air. JONATHAN G. KOOMEY, Lawrence Berkeley Nat'l Laboratory: When you multiply that out, what you get is about 8 kilograms of carbon per year for toasting bread every day. And if we convert it to pounds by multiplying by 2.2, we get about 20, 20 pounds of carbon per year associated with using a toaster. NARRATOR: Or consider central air conditioning. JONATHAN G. KOOMEY: A typical home in the South would use about 4,000 kilowatt hours for air conditioning. If we convert that to carbon emitted, we get about 800 kilograms of carbon emitted per year for a central air conditioner. And that's about 1,800 pounds, which is more than the weight of a small car like a Toyota Corolla. NARRATOR: Since each pound