Nature of Electricity
Electricity is difficult to store and has to be available on demand. It is not possible to keep it in stock. Unlike water or gas flowing through a pipeline, electricity is lost during transmission. As electricity travels along a line, a portion is lost in the form of heat. The extent of electricity lost in transmission and the level of congestion on any particular branch of the network will influence the dispatch of the generation units. To further complicate matters, supply and demand continually varies.