Hotel power is power generated on a train or boat which is used for purposes other than propulsion. Also known as hotel electric power (HEP), hotel power is used to provide various amenities to people on board, ranging from electric lights to heating. Power systems on boats and trains are often designed to allow independent control of the hotel power and the power used for propulsion, allowing an operator to control energy usage; for example, hotel power may be reduced on a train making its way up a grade to ensure that the train has enough energy to successfully climb the grade.
On a train, hotel power is provided by the locomotive or by a separate generator car. Trains today use what is known as head end power, meaning that energy is generated by a single source and sent throughout the train, in contrast with historical systems, in which each train car generated its own power. Hotel power provides energy for lights, outlets, stoves, heaters, and anything else which requires electricity to run.
Hotel power is essentially generated for the benefit and comfort of passengers, rather than as a necessary part of a train's operation, and is one of the services offered by the railway. The power generator is usually designed to ensure that the cars are powered even when the train is not in motion, so people can enjoy lights and other amenities when the train is in a station, temporarily shunted to a siding to allow another train to pass, or stopped for other reasons. As discussed above, hotel power can also be temporarily reduced or terminated to meet the power needs of the train.
On a boat, hotel power is more critical, because many electrical systems are important for safety and comfort on board ship, including climate control and desalination systems. Power generation can usually be controlled by making adjustments to the system, to meet varying power needs on board ship. During peak operation, for example, more auxiliary power may be needed, while in the dead of night, power requirements are generally fairly low.
Hotel power systems can get quite complicated, with each boat or train carrying along its own power plant and distribution method. Several companies specialize in creating, maintaining, and repairing power systems of this type, including companies which specialize in working with the military to supply some unique power needs which arise on military transports.