Diesel engines are also used to drive generators in isolated areas not served by power companies. Many hospitals, factories, and apartment buildings have diesel engines to drive generators in case the distribution of electricity from power plants is disrupted. The electricity generated by power plants is transmitted to cities or other areas. It is then distributed to houses, factories, farms, offices, and other consumers. Electric power delivery system Transmission.
Most electricity travels from power plants along overhead wires called transmission lines.
Laying underground or underwater cables generally costs more than stringing overhead wires. Cables are therefore used much less often than overhead wires. As electric current moves along transmission lines, the lines resist the current flow. The resistance causes the current to lose energy by heating the lines. Power plants limit energy losses by transmitting electricity at high voltages.