Aurora Botnia completes world’s largest marine battery retrofit

Aurora Botnia has been retrofitted with a new 10.4-MWh AYK Energy battery system that is nearly five times as powerful as the previous 2.2-MWh system on the hybrid-electric ferry. This brings the total energy storage capacity to 12.6 MWh.

The upgrade at Turku Repair Yard in Finland exceeds the previous biggest marine battery retrofit on the Aida Prima cruise ship by about 500 kWh, said a statement by UK-headquartered AYK Energy.

The upgrade is expected to slash fossil energy use by around 10,000 MWh annually, cutting emissions by nearly a quarter each year, as the vessel plies the green corridor route between Vaasa in Finland and Umeå in Sweden. 

The upgrade was started during normal operations and finalised at Turku Repair yard. AYK Energy built, supplied and installed the battery retrofit, with Wärtsilä and Foreship partnering in the project.

2021-built Aurora Botnia operates the battery system in combination with Wärtsilä dual-fuel LNG/LBG engines. 

AYK founder Chris Kruger said, “AYK is delighted to undertake this groundbreaking upgrade for Wasaline. The time for electric vessels has come. 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.”

When planning Aurora Botnia’s construction, Wasaline targeted achieving fully carbon-neutral operations by 2030, but achieved this ahead of time in 2025, by using biogas supplied by Gasum.

Wasaline managing director Peter Ståhlberg said, “The Vaasa-Umeå route is the first international green shipping corridor in operation. There’s growing demand for environmentally friendly transport in Europe and the entire transport chain can be carbon-neutral today. 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.”

Mr Ståhlberg told PST last year that originally, Wasaline considered retrofitting one engine with e-methanol. But a subsequent study found that the best payback would be deploying batteries. A major drawback for the use of e-methanol was planned methanol production in Sweden was postponed, meaning the wake-to-well journey would be so big that the methanol would not be as green once it arrived at the tank. 

In the last year, AYK has installed some of the biggest marine battery systems ever built, including two 12-MWh Orion+ batteries for Brittany Ferries’ hybrid-electric vessels Guillaume de Normandie and its sister ship Saint-Malo.