Norled: enter battery-hybrid ferry quartet

Norled is building four hybrid ferries, where major considerations include designing the automatic mooring and charging system

Norled is boosting the battery power in its fleet by constructing four double-ended diesel-electric hybrid ferries.

Remontowa Shipbuilding is constructing two which are due to be delivered in Q4 this year, with the remaining two to be delivered in 2020.

The new ferries will service the Festøya-Solavågen connection. They will be capable of carrying up to 120 cars and 296 passengers.

Remontowa Shipbuilding director of commerce Michal Jaguszewski says the main consideration is the “required delivery date which, taking into account when the shipbuilding contracts were signed, leaves only a year to construct the first two ferries. While this definitely is a challenge, Remontowa Shipbuilding has already proven to be capable of performing under very strict schedules. Ryfylke and Hardanger, also part of Norled’s fleet and delivered by our yard in 2013, required about 15 months to be finished despite being bigger and running on LNG which adds to the complexity.”

Remontowa is no stranger to building battery-hybrid ferries. Last year the shipyard delivered two vessels to Transport for London for river crossings on the Thames which operate in peak shaving mode with only one genset online and the remaining demand for power covered by the batteries. The new Norled ferries are intending to run in full electric mode with all gensets offline which, also due to the vessels’ size and the considerably longer crossings, results in the battery pack being much bigger.

Mr Jaguszewski says “Dimensioning and calculating the required propulsion and auxiliary power are of utmost importance in the perspective of Norled’s contract with the administration, which penalises excessive energy consumption.”

A fast charging solution will be used. In normal operation the required energy for propulsion and all consumables on board will be taken from li-Ion battery packs. The batteries will be recharged from the land grid during the vessels’ stay at quay, which will typically be about 11 minutes.

Mr Jaguszewski says “Having a fast-acting automatic system is a key feature for the required amount of energy to be transferred efficiently from the shore grid to the vessel’s side to ensure the required state of charge of the batteries is maintained.”

The shore charging system is used in combination with an automatic mooring system in some of the ferry terminals, holding the ferries when at quay and giving the green light for the charging process to start.

“Even if most of the equipment is arranged on the shore side for automatic shore charging and automatic mooring, it has been important to include these features in the design from the beginning to ensure the interface on the ship side is prepared for this equipment,” says Mr Jaguszewski.

“A ferry in Norway usually sails on a specific route for 10 years, and this means the solution developed for one specific route needs to allow for interface on other ferry connections for the rest of the vessel’s lifetime. A strong focus is given on how the solutions developed today will be universal for other routes in Norway.”

The ferries are built according to the LMG 120-DEH design developed by LMG Marin. The design LMG 120-DEH features many energy-efficient solutions including using heat recovery, full LED lighting, highly efficiency electric power transmission, demand-dependent HVAC system, low resistance hull design and weight-optimised construction using the Light Craft DNV GL notation.

The thrusters are pulling type units with vertically mounted permanent magnet motors ensuring high efficiency even at very low loads. The LMG 120-DEH design is also characterised by an innovative vehicle deck and accommodation arrangement that allows for fast and safe vehicle loading, significant energy savings and improved safety for crew and passengers.

Mr Jaguszewski comments “When a battery system is designed and selected, a strong focus must be given to the vessel’s specific operational profile. Batteries age due to the charging and discharging cycles they experience during their lifetime. To ensure the expected lifetime is achieved, a battery lifetime simulation is performed with the battery suppliers at an early stage.

“The simulation takes into account the vessels’ characteristics as well as the specific ferry’s operational profile. It has been an increasing focus to consider the vessel may be operating on a different route with a different speed, charging time and/or charging capacity in the future. Consequently, even if the battery system needs to be optimised for the first 10 years of operation, it is important to have a solution that can be upgraded at a later stage.”

The contractual makers list was agreed at the precontract stage. Mr Jaguszewski says that in the case of some of the “equipment, mainly the systems vital for the vessels’ operation (the electrical package to be delivered by Westcon Power & Automation), the owner had strong preferences,” while in other cases the yard was given the choice.

He says “We are very satisfied that a number of companies from Remontowa Holding capital group (Remontowa Marine Design & Consulting, Remontowa Electrical Solutions, Remontowa Hydroster Systems, Remontowa Lighting Technologies) are involved in the project.”