From Diesel Generators to Solar-Powered Berths: Practical Blueprint for Zero-Energy Ports

A modern seaport can resemble a small city in its appetite for electricity, when large vessels switch off their diesel generators and connect to power supplied from the shore. The original study, 'Smart Distributed Generation and Energy Storage for Nearly Zero-Energy Ports: Cold Ironing Optimisation Within a Collaborative Quality Framework,' published in Frontiers in Energy Research, explores how solar panels, battery storage, smart meters and shared energy governance could make this demanding process cleaner and more affordable.

Researchers Nikolaos Sifakis, Dimitrios Cholidis and George Arampatzis tested their framework at Italy's Port of Ancona, using genetic-algorithm optimisation to examine 12 energy scenarios rather than proposing one oversized system for the entire port.

A berthed ship behaves like an enormous electric vehicle

Cold ironing supplies electricity to a ship while it is docked, allowing the vessel to shut down the auxiliary diesel engines normally used for lighting, ventilation, refrigeration and other onboard systems. A passenger ferry may require between 2 and 16 megawatts for several hours, when some port connections can reach 24 megawatts, making one vessel comparable to hundreds or even thousands of electric cars charging at the same location.

This concentration creates a problem that ordinary EV networks rarely encounter: Road vehicles are spread across many charging points, while a ship can introduce a multi-megawatt step-load at a single berth within seconds, potentially causing voltage fluctuations, harmonic distortion and stress on the local distribution network. A battery placed close to the berth can soften these sudden changes, store surplus solar electricity and release power when a vessel's demand rises.

The proposed smart energy management system follows five priorities: use solar electricity directly, charge the battery with surplus production, export remaining power to the grid, discharge the battery to shave demand peaks, and import grid electricity only for the load that remains. Smart meters would collect second-by-second information from the grid connection, solar inverters, battery system and individual berths, while 15-minute records would support billing and the sharing of benefits among energy-community members.

Twelve scenarios reveal where solar and storage work best

The Port of Ancona consumes about 53.7 gigawatt-hours of electricity annually, with maritime traffic accounting for roughly 47 percent and industrial facilities close to 50 percent. The researchers examined four demand levels: port facilities alone, low-intensity cold ironing, major-vessel electrification and full cold-ironing coverage. Each was tested with grid electricity only, grid-connected solar power, and solar power combined with lithium iron phosphate battery storage.

A genetic algorithm searched for suitable solar and battery capacities while balancing the levelised cost of electricity and operational carbon emissions. The model used hourly weather data for 2023, historical vessel activity, a 25-year project lifetime, a five percent discount rate and a complete battery replacement in year 12. Solar power was used first, batteries operated with a 40 percent minimum state of charge to preserve capacity for unexpected ship arrivals, and the remaining electricity could be exchanged with the public grid.

The optimisation was placed inside a management structure based on ISO 50001 and ISO 37101. These standards turned broad ideas such as efficient energy use, environmental protection and responsible investment into measurable conditions, including acceptable energy costs, renewable performance, system availability, peak-demand reduction, carbon savings, battery health, payback time and investment return. Every recommended use case passed the applicable quality tests.

Dock-by-dock electrification delivers the strongest practical result

Solar generation produced the largest improvement across every demand scale, cutting the levelised cost of energy by 22.5 to 50.2 percent and lowering the carbon footprint by roughly 28.5 to 46.2 percent compared with grid-only operation. Batteries delivered additional savings by absorbing midday solar surpluses, limiting exports and releasing stored electricity during evening or overnight vessel demand.

The most environmentally effective and immediately practical option was the low-intensity dock configuration known as Scenario S6. It combines 12.9 megawatts-peak of solar capacity with a 12.4-megawatt-hour battery and a 16-megawatt shore connection. This arrangement reduced the operational carbon footprint by 56.04 percent, delivered electricity at €0.267 per kilowatt-hour, achieved an internal rate of return of 32.47 percent and recovered its investment in about 3.08 years. Its solar installation would occupy around 64,500 square metres, an area considered achievable on rooftops and nearby land.

Full electrification produced the cheapest electricity in absolute terms: Scenario S12 paired 30.2 megawatts-peak of solar power with an 18.6-megawatt-hour battery, reaching €0.211 per kilowatt-hour, a 36.12 percent internal rate of return and a 2.77-year payback period. Its carbon reduction was slightly lower at 52.48 percent, and the required solar area reached approximately 151,000 square metres, exceeding the space available inside the port.

Battery effectiveness declined as the system grew: The battery in the targeted dock configuration handled about one-third of average daily demand, while the larger battery in the full-electrification model covered a much smaller share of the greatly expanded load. Overnight grid consumption persisted, showing that lithium iron phosphate storage alone cannot turn a large port into a completely self-sufficient energy system.

Proven equipment still needs real-world testing and shared governance

Solar modules, batteries and shore-power equipment already stand at technology readiness levels 8-9, meaning the individual components are commercially mature. The complete solar-battery-cold-ironing system with coordinated energy management was assessed at TRL 6-7 because it has been validated through a detailed representative simulation but not yet demonstrated as one integrated system in an operating port. Governance readiness remains lower at TRL 4-6, making institutional coordination a greater obstacle than the hardware itself.

A port energy community could allow authorities, terminal businesses, ship operators and grid companies to invest together, operate shared infrastructure and distribute savings transparently. Such an arrangement must accommodate permanent port members alongside vessels that participate for only a few hours, establish fair benefit-sharing rules and negotiate grid agreements covering exports, medium-voltage connections and support services.

The simulation used one year of satellite-derived weather data, a projected vessel-demand profile, fixed electricity prices and a constant Italian grid-emission factor. Its hourly resolution could not reproduce the second-by-second voltage disturbances, and harmonics created when ships connect. Grid reinforcement costs were excluded, battery and solar degradation were applied after the simulation, and off-site renewable generation was not modelled in detail. These assumptions mean the study offers a strong planning framework rather than a final engineering blueprint.

The researchers recommend starting with dock-level clusters, collecting operational data and expanding as governance and technical experience mature. Future work should test the system at the Port of Ancona, study dynamic tariffs and emissions, model multiple weather years, examine vessel-to-grid electricity exchange, and add offshore wind, wave, tidal or green-hydrogen systems capable of covering longer periods when sunlight and ship demand do not align.