Wärtsilä claims integration on Aurora Botnia battery expansion project

Wärtsilä has confirmed its participation in the Aurora Botnia battery expansion project as electrical integrator for the Wasaline ropax ferry.

The project will increase the ship’s battery capacity by 10.4 MWh, from 2.2 MWh to 12.6 MWh, making it the world’s largest marine battery-hybrid system in operation. Wärtsilä reported the order in its Q3 2025 results.

In mid-August, Wasaline director of communications and sustainability Catarina Fant mentioned Wärtsilä’s participation in a conversation with Riviera that highlighted Wasaline’s use of sustainably produced biogas to power Aurora Botnia. The use of the drop-in fuel allowed the company to claim carbon neutrality in its single-vessel operation.

The deal that has suddenly allowed Wasaline to claim carbon-neutral operations of its ferry and the first fully operational international green corridor route in shipping is a three-way co-operation between Wasaline, major European ferry operator Stena Line, along with biofuel provider Gasum. 

For carbon neutrality, Gasum is enabling the use of certified biogas in the daily operation of Aurora Botnia, which is already equipped with batteries, and for which Wasaline has announced an upcoming project to extend the vessel’s battery capacity of 10.4 MWh. 

Ms Fant said the battery extension project on the approximately three-year-old vessel is slated for the vessel’s next drydocking, sometime late in 2025 or early 2026. After the conversion to add battery capacity, a four-party collaboration with AYK Energy, Foreship and Wärtsilä, Aurora Botnia will have the biggest battery capacity on a ropax, said Wasaline, with a total of 12.6 MWh.