Marine battery manufacturer AYK Energy has completed what it describes as the world’s largest battery retrofit on the hybrid-electric Ro-Pax ferry Aurora Botnia, operated by Finnish shipowner Wasaline.

The project, carried out at Turku Repair Yard in Finland, involved installing a 10.4 megawatt-hour (MWh) AYK Pisces+ battery system. The new installation replaces the vessel’s previous 2.2 MWh unit, increasing the vessel's total onboard energy storage capacity to 12.6 MWh. According to AYK, the upgrade surpasses the previous largest marine battery retrofit, on the cruise ship Aida Prima, by around 500 kWh.

The vessel has now returned to service on its year-round route between Vaasa, Finland, and Umeå, Sweden.

“AYK is delighted to undertake this groundbreaking upgrade for Wasaline. Our companies share a passion for innovation and decarbonisation,” AYK founder, Chris Kruger, said. “It is especially pleasing for AYK to deliver this project on time and on budget. The time for electric vessels has come.”

Aurora Botnia operates its battery installation alongside Wärtsilä dual-fuel LNG/LBG engines on the Vaasa–Umeå service, described as the first international green shipping corridor currently in operation. AYK said the expanded battery capacity is expected to further reduce emissions on the route.

Peter Ståhlberg, managing director of Wasaline, commented: “Expanding our battery capacity with AYK Energy is a major step that allows us to make our vessel even more sustainable. Our collaboration with Finland’s and the region’s energy clusters makes innovative solutions like this possible.”

Wasaline had originally targeted full carbon-neutral operations by 2030, but states that this objective was achieved in 2025 through the use of biogas.

Kruger added: “Marine battery technology is improving so fast, with superior levels of energy density, safety and cost savings. The Aurora Botnia retrofit shows what is possible. Hybrid ships have a very big future, not least because the ROI is so fast. Battery systems can pay for themselves within just a few years in fuel savings.”

AYK reported rising demand for its battery systems across multiple vessel segments, including cruise ships, icebreakers, ferries, workboats and container vessels.

Over the past year, the company has delivered two 12 MWh Orion+ battery systems for Brittany Ferries’ hybrid-electric vessels Guillaume de Normandie and Saint-Malo, and has agreed to supply a 6 MWh battery for what is described as the world’s first battery-methanol tug for Svitzer.