Electricity transmission lines provide the transport highways to move electricity from the generation sources to concentrated areas of customers. From there, the distribution system moves the electricity to where the customer uses it at a business or home. The transmission systems are unique because they are designed to move this energy at the speed of light from the generator to the consumer since there is no long-term storage capability for electricity. Electricity, when transmitted, flows over all available paths to reach the customer and it cannot be easily directed in one particular way. Therefore, the buying and selling of electricity requires direct coordination and proactive monitoring of the electrical systems. If a problem develops somewhere, the impact affects other operations elsewhere. To handle this coordination, 10 industry reliability councils were established that operate the three power grids in the United States. Electrical reliability is a major responsibility of transmission management. Within each of these power grids, there are different types of equipment and facilities that are owned by many different entities. Each system is operated in a coordinated and unified manner within its power grid but since the three power grids are not simultaneously linked together, electricity (alternating current power) cannot flow between them.
Greater competition in electricity markets has expanded the use of the grid. The grid, built originally to interconnect neighboring utilities, is now being used as a superhighway for electric companies, resulting in tremendous congestion.
Returns on transmission investment may be too low to attract the large amounts of capital needed to expand and upgrade the grid, and encourage the development and use of new technologies to enhance its efficiency. At a time when the transmission system is nearing the limits of its capacity, investments in transmission have actually been declining. For example, Transmission investments in 1999 were less than half of what they had been in 1979.