Yes, all true. But, you also need to keep the "pots" quite warm (at least 960 degrees C) in order for the electrolyte to be liquid. Keeping them that temperature while not actually producing any product (while electricity is expensive) is a waste. The article you cite says that the Australian smelters that are used to iron out changes in electricity demand can't be switched off for more than 4-5 hours, or they may be damaged by the liquid solidifying.