While appliances have become more efficient, consumers have larger homes, use more air conditioning, and have more electronic devices than they ever have before.
As well as high demand, electricity rates are rising. These increases reflect a multitude of factors. Fuel prices are rising. Old power plants are being replaced, especially coal-burning plants, which, though they are cheap to operate, have been deemed environmentally unfriendly under the EPA's Clean Air Act.
USA Today has a fantastic article on the subject here.
Jesse M.