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Wärtsilä and Wasaline Lead World’s Largest Marine Battery Hybrid Project

Wärtsilä and Wasaline expand the Aurora Botnia’s battery system to 12.6 MWh, setting a new global record and reinforcing their commitment to sustainable ferry operations across the Baltic

26 Sep

Edited September 26, 2025

Content by Powerboat & RIB

Ferry sailing at sea with Wasaline branding, showcasing sustainable hybrid propulsion technology.

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Expanding Aurora Botnia’s Green Credentials

Technology group Wärtsilä has been selected as the electrical integrator for a landmark project to expand the battery capacity of Wasaline’s ROPAX ferry Aurora Botnia. The upgrade will increase capacity from 2.2 MWh to 12.6 MWh, making it the world’s largest marine battery hybrid system in operation. The order was confirmed in Q3 2025, with commissioning scheduled for early 2026.

Pioneering Hybrid Propulsion

Hybrid propulsion systems, combining energy storage with conventional engines, are helping shipping reduce greenhouse gas emissions. The Aurora Botnia, already equipped with dual-fuel engines running on biogas and batteries, will now take a further step in sustainability with Wärtsilä leading the integration. The project includes delivery of an Energy Management System, upgraded power drives and improved control system integration.

Strengthening Collaboration

The Aurora Botnia serves as a floating test laboratory connected to Wärtsilä’s Sustainable Technology Hub, advancing the development of hybrid technologies. This collaboration builds on the existing agreement between Wärtsilä and Wasaline, reinforcing both companies’ commitment to optimising efficiency and cutting emissions.

“Wasaline’s commitment to decarbonised shipping operations is central to everything we do. In this, our close cooperation with Wärtsilä is an essential element that benefits not only both our companies…but sets standards for the whole marine sector.

Peter Ståhlberg, Managing Director of Wasaline

This project will optimise operations further, creating fuel savings and significant reductions in emissions.

Roger Holm, President of Wärtsilä Marine & Executive Vice President at Wärtsilä Corporation

MDL mpu with Rest Easy this Winter text on

A Ferry at the Forefront of Sustainability

Since entering service in 2021, the Aurora Botnia has operated between Vaasa, Finland and Umeå, Sweden, featuring four Wärtsilä 31DF engines. These ultra-low emission engines have already reduced methane output, while the expanded battery capacity will strengthen its position as one of the world’s most sustainable ferries.

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