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WPCI - OPS -

Onshore Power Supply

Equipment and solutions

Systems not always interoperable
The required equipment and solutions may differ from case to case. At the moment systems across the world are not interoperable, differing in their voltage and frequency as well as structural design. This is due to the lack of standardization and the difference in system frequencies between the North American continent/parts of Japan (60 Hz) and the rest of the world (50Hz).

In addition, voltage levels differ among ports. Generally speaking, the first-generation OPS systems operate on low voltages. More recently, high voltage has become the standard, because of its easier operation in view of the limited amount of cabling required. For certain classes of vessel, however, matching voltage and frequency does exists. The cruise terminals in Juneau, Vancouver, Seattle and soon in Los Angeles all offer 11 kV and 6.6 kV to cruise ships. For voltage and frequency levels at different ports all over the world, click here.

Varying electrical frequencies
Electrical frequencies also differ among vessel categories and sizes. Ocean-going vessels calling at European ports tend to have more 60 Hz electrical systems onboard, while smaller vessels have 50 Hz systems. The latter are primarily smaller vessels not not sailing to other continents.

Vessel type

50 Hz

60 Hz

Container vessels (< 140 m)

63 %

37 %

Container vessels (> 140 m)

6 %

94 %

Container vessels (total)

26 %

74 %

RoRo- and vehicle vessels

30 %

70 %

Oil and product tankers

20 %

80 %

Cruise ships (< 200 m)

36 %

64 %

Cruise ships (> 200 m)

-

100 %

Cruise ships (total)

17 %

83 %

Source: Shore side electricity, A feasibility study and a technical solution for an on-shore electrical infrastructure to supply vessels with electric power while in port, Chalmers University

It will thus depend on the particular local situation whether or not a frequency converter and/or an onboard transformer are needed. As stated earlier, these two items will affect the overall costs of an OPS system.

Power requirements at berth
For an idea of the kind of power required for an OPS system, the power requirements of various vessel types and sizes are presented below. The figures cited for smaller vessels are representative for ships operating in European waters, but may also apply to other regions. Power requirements have a significant impact on the costs of an OPS system and it is therefore important to pursue energy reduction options and assess peak power demand in advance. 

Vessel type

Average power demand (MW)

Peak power demand (MW)

Peak power demand for 95 % of vessels (MW)

Container vessels (<140m)

0.17

1

0.8

Container vessels
(> 140 m)

1.2

8

5

Container vessels (total)

0.8

8

4

RoRo- and vehicle vessels

1.5

2

1.8

Oil and product tankers

1.4

2.7

2.5

Cruise ships (< 200 m)

4.1

7.3

6.7

Cruise ships (> 200 m)

7.5

11

9.5

Cruise ships (> 300 m)

10

20

12.5

Partly based on: Shore side electricity, A feasibility study and a technical solution for an on-shore electrical infrastructure to supply vessels with electric power while in port, Chalmers University

Container terminals need more connection points
For vessels like tankers, cruisers and RoRo vessels that commonly berth at the same dock and do not use cranes, shoreside connection is easier. At container terminals, where vessels do not always dock at the same position, there is a need for more connection points.

At container terminals the area at the quay is restricted by rails, which makes quayside space more limited.