EDF is building a fallacious case for justfying forthcoming brownouts, as generation capacity is reduced.
The article says, "Many appliances, including incandescent lighting, work just as effectively, yet consume less energy, when the flow of electricity to them is reduced.", yet you know that the lights dim when the voltage drops.
Reducing voltage supplied actually causes more energy loss in the transmission and distriubtion system, as currents rise as demanded by voltage regulators, computer power supplies, electric motors, etc in response to voltage drops.
Simple resistive heaters like stove-tops will draw less current at less voltage, reducing the rate of energy consumption, but they will operate longer bring a post of water to boiling.