Wasaline: swedisch Ferry Operator to install more batteries and methanol for ferry Aurora Botnia
c: Wasaline
With its dual-fuel LNG engines, the option to run on biogas, and zero-emission batteries supported by extensive use of shore power, the 2021-built ferry Aurora Botnia is already notable for its green profile.
Now, Wasaline has contracted Foreship to evaluate an extension of the battery energy storage system (BESS) and an e-methanol conversion.
The Super 1A Ice Class rated passenger/freight ferry Aurora Botnia serves the vital 52-nautical-mile Kvarken Link route, undertaking twenty to 24 crossings a week between Vaasa in Finland and Umeå in Sweden – two port cities with strong reputations for environmental responsibility.
Foreship also supported Wasaline through the 2021 delivery at Rauma Marine Construction shipyard and provided knowledge of the use of BESSs on ships for spinning reserve/blackout prevention, peak load shaving, load response, and zero-emission operations.
Feasibility study
With IMO targets for ship emissions tightening, and EU penalties and incentives to accelerate low-carbon fuel uptake from 2025, however, Wasaline asked Foreship to prepare a feasibility study on a possible extension or replacement of Aurora Botnia’s existing BESS earlier this year.
The two-part project also foresees an evaluation of the technical impacts and business case for a partial engine conversion from LNG to e-methanol dual-fuel.
‘In a relatively short period, the potential of batteries to offer a bigger contribution to zero-emission ship power has advanced rapidly,’ says Joonatan Haukilehto, Head of New Technologies, Foreship.
Twelve different battery extension options
Foreship’s battery study evaluated twelve different BESS extension possibilities for return on investment and technical complexity. ‘We based our analysis on the improved energy efficiency of the vessel and the low price of shoreside electricity and factored in the shelter and cost incentives the energy type will offer under EU emissions arrangements,’ explains Haukilehto.
Based on complexity, cost, stored energy, power, and regulations, Foreship identified multiple scenarios to replace the existing 2.2 MWh BESS with a 6-8 MWh capacity system without major structural or electrical infrastructure work. In addition to evaluating the replacement of the existing BESS with many years of usable life ahead, Foreship evaluated keeping the NMC-type installation as-is, and adding another battery storage space, thus increasing BESS capacity to 10-14 MWh.
Haukilehto: ‘With cheap electricity available from shore power not only covering 100 per cent of the ship’s power needs during port stays, but also charging batteries, the retrofit could contribute up to twenty per cent of overall ship energy needs. ‘Furthermore, the vessel’s total energy efficiency is clearly improved by the possibility to run on a single engine on high load for the majority of voyages.’
Methanol conversion
The potential engine conversion to run on methanol would be quite straightforward, adds Haukilehto, given that many of the systems could use the same routing as existing LNG-related systems. While a separate methanol fuel treatment room would need to be factored in, fuel storage space would not be a major factor, given the short voyage involved and a favourable existing tank arrangement, he says.
About the Aurora Botnia
The Aurora Botnia, delivered in August 2021, was built by Rauma Marine Constructions (RMC), a fully domestically owned Finnish shipbuilding company founded in 2014 after Korean STX retreated from Finland. RMC has tried to make the Aurora Botnia as environmentally friendly as possible with the technological know-how and possibilities available at the time the ship was built three years ago.
Classed by DNV, it got the CLEAN (design) class notation. This means that the ship complies with requirements for minimisation of harmful operational emissions to air and sea. In the design, additional requirements were included for protection against accidents and for limiting their consequences. In the operational requirements, it is stipulated that an environmental officer is appointed.
Refrigerants and firefighting substances are non-ozone depleting. The holding tanks’ capacities are built in with extra distance to bottom and side, spill trays, etc. To comply with the rules of the Recyclable class notation, an inventory of hazardous materials is maintained.
The Aurora Botnia is equipped with diesel-electric propulsion consisting of four 31DF (dual fuel) Wärtsilä engines and two azimuthing pulling thruster units (from ABB Azipod) for high efficiency and manoeuvrability. For the exhaust gas and cooling of the engines’ water systems, it is equipped with a waste heat recovery system. Additionally, the cold energy of the LNG system is recovered for other cooling purposes.
Throughout the ship, LED lighting has been used. The heating, ventilation and air conditioning (HVAC) system has an energy saving mode for cabins that are not occupied. For garbage and waste management, the recycling level is as high as reasonably practicable. Nothing is dumped to the sea. Antifouling is applied only to limited areas, which are not cleared by ice during the winter. The food offered on board is locally produced as much as possible.
The Aurora Botnia is normally operated on LNG, but can also run on biogas or, in the future, on e-methane as main fuel. For zero-emission operation in port proximity and peak power shaving and power boost during manoeuvrability or operations in ice, the ship has a battery pack of 2.2 MWh. For electrical supply in ports, the Aurora Botnia has a shore power connection. On each side, the ferry has 2 MW capacity for battery charging and hotel load. So in port, the ship is emission-free.