When ships are docked, power is still needed for electricity generation on-board. Instead of running on-board generators, ships can be coupled to the land-based power grid. This avoids running the relative inefficient and polluting on-board generators for the days in the port.The infrastructure of the port electric installation necessary for the ships’ supply has to be designed so as to make the operating of different ship types possible. It is complicated as all over the world ships are equipped with different electric systems, the infrastructure needs to take this onto account. Typically this is more straightforward when the fleet of ships using the facilities is predictable and recurrent (e.g. ferries).