This is still largely true, but a new product has entered the scene: a residential heating appliance that can create electricity from the energy it's already using to create the heat. It's a collaboration between Climate Energy LLC and American Honda Motor Co.
The technology is called combined heat and power (CHP), and industrial systems have been using it for some time. Converting heat energy into electricity is the basis of most power plants. Doing it on such a small scale, though, is new. It's like having a miniature power plant attached to a customer's furnace or boiler. And it's here now.