Onshore Power Supply: For a Greener Future

What OPS Is and Why It Matters

Onshore Power Supply — known in the industry as cold ironing or Alternative Maritime Power — is the practice of connecting a vessel at berth to the port’s electrical grid, allowing its auxiliary engines to be shut down entirely during the port stay. Those auxiliary engines, which would otherwise run continuously to power lighting, ventilation, refrigeration, and onboard systems, are a significant source of localised air pollution at ports. Particulate matter, nitrogen oxides, sulphur oxides, and carbon dioxide emitted at berth affect port workers, nearby communities, and coastal ecosystems in ways that are both well-documented and increasingly unacceptable to the regulators and communities that ports depend on for their operating licences. OPS eliminates that emission source at its root, replacing engine combustion with grid electricity that can increasingly be sourced from renewable generation.

The environmental case has been understood for decades, but OPS has historically struggled with the capital investment required, the compatibility challenges between vessel electrical systems and port infrastructure, and the absence of regulatory compulsion to drive adoption. That picture has changed materially. The FuelEU Maritime Regulation, which took effect in January 2025, mandates OPS use at EU ports and introduces fines and port access restrictions for non-compliant vessels and operators. Cold ironing has moved from a voluntary sustainability credential to a compliance requirement — and the infrastructure investment required to meet that requirement is now a strategic priority for ports and shipowners alike.

The Environmental and Operational Benefits

The Regulatory Landscape

The FuelEU Maritime Regulation that entered into force in January 2025 represents the most significant regulatory driver for OPS adoption in Europe. It mandates that vessels use shore power while at berth at EU ports, with non-compliance triggering financial penalties and potential restrictions on port access. The regulation also introduces monitoring and reporting requirements for energy use at berth, creating a transparency obligation that will make OPS performance visible across the fleet. Public funding mechanisms are available in some jurisdictions to offset infrastructure investment costs — a recognition that the scale of port electrical infrastructure required to meet demand presents a genuine barrier that market forces alone may not overcome.

In the United States, California’s At-Berth Regulation has been the primary driver of OPS adoption, mandating shore power use at six major California ports for container, cruise, and refrigerated cargo vessels. Expansion programmes at ports in Galveston, Miami, and Philadelphia reflect the regulatory trajectory: what begins in the most stringent regulatory jurisdictions tends to set the standard that others follow. Operators who have invested in OPS infrastructure and vessel retrofits ahead of mandatory requirements are now positioned to call at these ports without compliance risk and to benefit from any port access preferences that accrue to OPS-equipped vessels.

Challenges and Practical Considerations

The barriers to OPS adoption are real and should be addressed directly. The initial capital investment required — for port-side electrical infrastructure, vessel connection systems, and any necessary grid upgrades to handle the 2 to 12 MW power demands of berthed vessels — is substantial. Economic analyses of the full lifecycle cost-benefit for individual shipowners are less available than the industry needs, making investment decisions harder to justify internally without clear financial models. Compatibility between the electrical systems of different vessel types and the standardised shore connection infrastructure at ports requires careful technical coordination, and the shift toward alternative fuels on some vessel types introduces additional complexity around what shore power infrastructure will ultimately be needed.

Community engagement is a consideration that port authorities are increasingly recognising as essential to successful OPS infrastructure development — particularly where projects involve renewable energy generation on or near port land. Navigating planning processes, addressing community concerns about visual impact and land use, and communicating the air quality benefits of the project to local stakeholders are all components of successful infrastructure delivery that purely technical approaches to OPS planning can overlook.