Motivation

Electric utilities are expected to provide uninterrupted service. To fulfill this expectation, utilities use a range of energy storage technology so that electricity can be produced in the most economical and efficient manner. Gasoline refined from crude oil is drawn from an underground storage tank when a driver replenishes the fuel in an automobile. Imagine the difficulty meeting the demands of the drivers if the crude oil had to be refined at the time of the replenishment. The task is imposing because consumer demand varies throughout the day and throughout the year. The same is true for utilities providing electricity to consumers.

A large electric power plant produces electricity on consumer demand, and the utility must be prepared to meet demands that vary throughout the day, the week, and the year. The demand is divided roughly into three parts termed baseload, part time, and peak...