Ground Power Unit , a device used on the ground at Airports to supply Aircraft without an APU with electric Power . It is also used by aircraft with APUs if the airport authority does not permit the usage of APUs at its docks or if the carrier wishes to save on the use of jet fuel (which APU's use). The most common form of GPU is a small vehicle or trailer with a DieselGenerator although units fueled with gasoline are not unknown. There are also all-electric units that are powered off of the local electrical grid.
