Shore power at the berth: substations, ducts, load balance and commissioning

March 10, 2026

By Editorial Staff

Electrifying a port means organizing a network able to supply ships at berth, yard equipment and terminal services, and translating the single-line diagram into spaces, routes and civil works that can actually be built on a working quay. Before choosing substations and equipment, a balance of loads, simultaneity and expansion phases must be built and checked against the continuity of existing operations.

Power and energy: the data to collect

The design starts from the ship profile: power demand, length of stay, voltage, frequency and the availability of on-board connection interfaces. For the port, the number of ships connected at the same time matters too: the rating of a single outlet does not guarantee that the grid can supply all berths at once.

A simple illustrative example clarifies the distinction. A ship drawing an average of 4 MW for eight hours of effective connection receives 4 × 8 = 32 MWh. Two such ships connected at the same time need 8 MW on average, while peaks must be assessed separately. If the overall efficiency between grid withdrawal and delivery is 95%, delivering 4 MW requires about 4.21 MW from the grid. These figures do not describe a real port; they separate energy, which drives consumption and revenue, from power, which drives the size of electrical infrastructure.

From the census of users to available capacity

Shore power for ships, charging of electric yard equipment and fixed terminal services have different absorption profiles, durations and simultaneity. Adding nominal ratings does not describe real demand, and a daily average is not enough to size the network: peaks and operating constraints must be examined separately. Discussions with the grid operator must precede the works program, because connection capacity, activation times and line routes can delay commissioning more than equipment delivery.

Substations and ducts are port structures

Substations need maintenance access, ventilation, protection from the saline environment and a location consistent with flood risk and future sea levels. Duct banks must cross yards and quays without interfering with existing utilities, crane rails, crane foundations and mooring equipment. An incomplete survey of existing networks often forces trenches to be redesigned during construction.

On operating quays work proceeds in phases: fencing of areas, alternative routes, installation of ducts, reinstatement of pavements and testing. The sequence must be agreed with the terminal, stating when each berth will be available again and with what limitations. A duct that is accessible on an empty quay may become unreachable when a ship, vehicles and equipment are present, so the solution must be checked against a plan of space occupation in operation, not only against the plant layout.

Shore power and charging: two different needs

Cold ironing supplies the hotel and service loads of a moored ship. Charging transfers energy to an on-board battery system. The two functions can coexist but require specific checks on interfaces and service times, as discussed in the EMSA guidance on shore-side electricity. Compatibility of voltage, frequency, protection and control follows the IEC/IEEE 80005 family: part 1 for high-voltage connections, part 2 for data communication, part 3 for low-voltage systems; the applicable part and edition must be stated in the specification.

Storage and local generation: check the real benefit

Battery storage can shave some peaks if its power and energy capacity match the duration of the loads, but it does not automatically replace an adequate grid connection. Photovoltaic generation must likewise be compared with load timing: the energy produced over a year and the energy available during a specific call are not the same thing.

The European framework

The AFIR regulation (EU) 2023/1804 sets the availability of onshore power supply in TEN-T maritime ports meeting the traffic criteria of its article 9; the thresholds depend on ship type and number of calls, so it is not a blanket obligation for every berth. FuelEU Maritime adds an obligation of use: from 1 January 2030 container and passenger ships within its scope must connect to OPS, or use equivalent zero-emission technologies, in those ports, and from 2035 in all EU ports equipped with OPS.

From civil preparation to handover

Handover must include correspondence between as-built works and documentation, identification of circuits and the results of the tests required by the design. Functional tests of the connection require coordination between terminal, plant and ship. Electrical availability alone does not prove that the cable management system can be used in every permitted operating condition, so tests must include real connection and disconnection sequences with the vessels expected at the berth.

Measuring the service

Installed power should be complemented by energy delivered, share of compatible calls actually connected, connection time, plant availability and cost of service. Any emission benefit must be calculated against an explicit reference case, considering avoided fuel, losses and the electricity mix. Without port and shipowner data it is not correct to quote a universal cost per berth or a standard payback time.

AFIR and FuelEU also show why regulation must be built into port projects from the outset. As Fincosit engineer Alessandro Mazzi has argued, compliance can no longer be treated as a separate phase: it has to be designed into the project itself.

Technical assessment

Preparing a quay for cold ironing means reserving spaces and routes that must remain compatible with terminal operations for many years. Ducts, substations and connection points interfere with drainage, crane rails and cargo handling: resolving these interferences in design costs much less than adapting the structure later. Measuring the result as an available service, rather than as installed capacity, keeps the project focused on what ships and ports actually need.

Sources and further reading

Photo: Webuild, We Build Value