Fully Electric Ferry: Battery Strategy and Charging Infrastructure -- H Nordic Maritime

The starting point was 85 to 100 MWh onboard and 30 MW at the harbour. Our contribution was not an engineering specification -- it was a fundamental rethink of the underlying logic.

When a shipping company approached HNordic for strategic advice on their fully electric ferry concept, the starting point was an onboard battery capacity of 85 to 100 MWh and a shore-side charging requirement of over 30 MW. Both figures carried enormous consequences for capital expenditure, grid infrastructure, and long-term operating economics.

Our contribution was not an engineering specification. It was a fundamental rethink of the underlying logic.

The shift

From full charge to battery exchange

The conventional approach to electric ferry design places the full energy burden on the vessel itself, sizing the battery pack to cover the entire route from a single charge. We challenged that assumption. By introducing a RoRo-based battery exchange concept, where battery modules can be swapped or rotated between trips rather than fully recharged while docked, the actual onboard battery requirement dropped from 85 to 100 MWh down to 25 to 30 MWh. That is a reduction of around 70 percent, achieved not through better battery chemistry but through better systems thinking.

The downstream effects of that single strategic shift were significant across every dimension of the project.

Electric ferry at harbour with battery exchange infrastructure alongside

Grid connection

From infrastructure challenge to standard installation

Charging power demand at the harbour fell from over 30 MW to approximately 5 MW. This transformed the grid connection from a major infrastructure challenge, requiring costly upgrades and potentially years of permitting and civil work, into a manageable and straightforward installation. Grid stability, which is a growing concern for port operators as electrification accelerates across maritime traffic, was preserved rather than stressed.

Fleet economics

Shared capital across the programme

The battery modules themselves, now standardised and interchangeable, can be deployed across sister vessels in the same fleet as those ships are delivered. Rather than each new ferry requiring its own full battery investment, the capital cost is shared and spread across the programme. The reduction in total capex over a multi-vessel fleet is substantial.

What changed

Before and after

85--100 MWh → 25--30 MWh

Onboard battery requirement -- a 70% reduction through systems redesign.

30 MW → 5 MW

Shore-side charging demand -- a standard grid connection instead of a major infrastructure project.

This project reflects something we consider a core strength at HNordic. The best solutions rarely come from optimising within existing constraints. They come from questioning whether those constraints need to exist at all.

Fully Electric Ferry: Battery Strategy and Charging Infrastructure

From full charge to battery exchange

From infrastructure challenge to standard installation

Shared capital across the programme

Before and after

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