The innovation project, named the FIN-SWE-EC project, aims to retrofit the two 2023-built RoPax vessels, FINNSIRIUS and FINNCANOPUS, operating on the Naantali–Kapellskär corridor between Finland and Sweden.

The project will upgrade each vessel with an additional 25 MWh Battery Energy Storage System (BESS), increasing the total installed battery capacity to approximately 30 MWh per vessel.

The key innovation of the project lies in the deployment of very large-scale battery hybridisation on a long, year-round Baltic route, which introduces advanced energy-management across propulsion, hotel load and thermal systems, overcoming shoreside charging constraints, grid capacity needed to deliver that power during short port turnarounds.

Following retrofits in 2028–2029, commercial operation will begin in January 2030. The project is expected to avoid about 36,000 tonnes CO2e per year (363,000 tonnes over 10 years), a reduction of about 55% compared with fossil-fuel operation, and to provide a replicable template for electrifying RoPax services across Europe.

The six maritime innovation projects covering ammonia propulsion, vessel electrification, offshore charging and onboard carbon capture. They form part of a EUR 3.4-billion selection spanning 77 projects. Grant agreements remain under preparation, with funding terms and implementation requirements still to be finalised.

© Shippax

Part of FINNSIRIUS' current 5 MWh battery pack. © Søren Lund Hviid