Since the installation of the first electrical power plant late in the 19th century, the business of supplying electricity to industry and residences has been “on demand.” When you flip a light switch in your home, you expect the light to go on. For this to happen, electricity has to flow to your light bulb through an elaborate transmission and distribution network (T&D) of copper wires. These wires ultimately connect your light bulb to a generator that sits dozens if not hundreds of miles away from you. When you turn on your light bulb, there is an additional demand in electricity, and that generator “works a little harder” to supply this required electricity. This is what I mean by “on demand.” On a hot summer afternoon, the demand is large, and these generators are working near or at full capacity. At night, the demand is lower, and there is available excess capacity.