AC or DC Charging Is Becoming a Strategic Choice for Passenger Vessels
As electric passenger vessels move from pioneering projects into wider deployment, the question of AC or DC charging is becoming a practical infrastructure decision for ports, operators and vessel designers.
Passenger vessel electrification is entering a more operational phase. The question is no longer only whether ferries, shuttles and service vessels can run on batteries. Increasingly, the harder question is how ports and operators should charge them.
A recent op-ed by Sveinung Odegard, President of Zinus Power LLC, makes that point clearly. The industry is now facing a common-infrastructure challenge: how to provide charging systems that work across different vessel types, routes, harbours and operating models.
The choice between AC and DC charging is not a simple technical preference. It shapes where equipment is placed, who carries the cost, how much weight is added to the vessel, how flexible the vessel remains over its lifecycle and how much investment is needed on the shore side.
AC charging is more widely established and builds on shore power standards already used across the maritime sector. It can give the vessel greater control over the charging process and may be useful when vessels are expected to operate in multiple locations. The trade-off is that more conversion equipment is required onboard, adding cost, weight and space requirements.
DC charging changes that balance. It can reduce equipment onboard and push more of the conversion infrastructure to the shore side. That may be especially relevant where multiple vessels use the same route or charging location. It also creates opportunities to serve other electrified assets nearby, including heavy-duty road transport and port equipment.
For ports, this is where the discussion becomes strategic.
AC may offer flexibility and familiarity. DC may offer a stronger pathway for standardised, high-power charging infrastructure. Neither answer is universal. The right choice depends on route profile, vessel size, dwell time, ownership model, future redeployment and available grid capacity.
The standards discussion is equally important. The maritime sector has already built international shore power standards around AC connections, including low-voltage and high-voltage frameworks. DC standards are now emerging, with work underway on IEC/IEEE P80005-4 for DC shore power up to 1,500VDC.
At the same time, land-based charging standards are entering maritime conversations. CCS is already familiar, but its power ceiling is limited for many larger maritime applications. Megawatt Charging Systems are becoming more relevant because they are designed for much higher power levels, with architecture that can move into the megawatt range.
The wider lesson for DTF Conference readers is that charging infrastructure is becoming one of the decisive questions in maritime electrification. Wabtec's high-power ferry charging, Norled's SHIFTR battery swapping and smaller electric vessel projects such as Hyke all point to the same conclusion: ports will need multiple charging models, not one universal answer.
This is not only an engineering debate. It is a business-case debate, a standards debate and a port-planning debate. The ports that move early will need to understand not just how much electricity future vessels require, but what form that electricity should take at the quay.
Key Information And Statistics
- AC charging requires more equipment onboard but can give the vessel greater control over charging.
- DC charging can reduce onboard equipment but requires greater shore-side infrastructure investment.
- AC shore power standards include IEC PAS 80005-3 for low-voltage shore connections and IEC/IEEE 80005-1 for high-voltage shore connections.
- IEC/IEEE P80005-4 is under development for DC shore power up to 1,500VDC.
- CCS charging is already used in some contexts but typically reaches capacity limits around 350-400kW.
- Megawatt Charging Systems are designed for much higher power levels, with potential to reach the megawatt range.
- The charging decision depends on operating route, dwell time, vessel lifecycle, ownership model, weight, space and grid capacity.
