Technical issues for the ship owner
The absence of standardization for ships can be a problem as ships built in different places in the world have different voltage and frequency. There are no standards for the onboard voltage, but common voltages are: 400VAC, 440VAC, 690VAC for a LV electrical system and 6,6KVAC and 11KVAC for a HV electrical system. The frequency on a ship are normally 60Hz but 50Hz is not negligible.
Therefore, the shipowners stand in front of some heavy investments to be able to convert their ships to OPS.
Some example of retrofits that might have to be done is as follows:
Modification of the main switchboard, a new receiving circuit breaker close to the power receiving point, a transformer to comply with the ships voltage, ships couplers and an upgrade of the ship power management system. A safety monitoring system that connects to the port switchgear is also needed. The ships also need to build a room and a door in the hull to be able to receive the OPS cables/connectors.
Finally, the owner of the ship will have to request a certification of the installation from the classification societies.
Technical issues for the port
To be able to use OPS in a port the available power from the grid is a limiting factor. Different ports have different possibilities to offer enough power to the ships. If the power is not enough it will mean heavy investments for the port. For smaller ports this can be hard to achieve.
An OPS installation typically requires a house, container or a shelter, with the necessary technical equipment such as switchgear, transformers, frequency converters and monitoring system. Cables must be laid between the equipment and to the ship’s connection point at the quay. Cable reel arrangement must be places at the quay together with a crane to lift the cables up to the ship OPS intake. Finally, a safety monitoring system that connects to the ships switchgear is needed.
The OPS installation is likely to be very different from one port to another. It mainly depends on the ship type and the power demand: the higher the power demand is, the more investments is required. If the frequency used onboard does not match the frequency at the ports electrical grid, a frequency converter must be installed at the port side.
For smaller ports, it might be an option to use a standalone power source such as windmills or power cells changing batteries or an environmental better fossil/non-fossil fuel-driven power plant placed locally at the port. The latter could also be a mobile plant that can be moved between different ports.
Planning the connection details between all parties
Before the first connection between the shore and the ship there are several details that need to be discussed and agreed upon. The standards need to be discussed and a combability assessment performed. The location of the OPS system onboard and at the quay needs to be assessed, the voltage, the frequency and the power needs to be evaluated and measures taken to match these.
The PIC: s (Persons In Charge) need to have the sufficient education of the system they will operate. The standard also calls for synchronized periodic maintenance to be done on the ships and port equipment. The periodic maintenance must be documented and should be accessible for all parties.
Other factors that might affect the connection possibility
Different vessels stay in port different time. It depends, among others, on the cargo and availability of the handling capability in the port. Due to environmental effects for stopping and starting the onboard generators a too short port stay will not benefit to the emissions. A figure of minimum 4 hours is a time that tends to be commonly used.