Battery-hybrid vessels

The Strynø ferry (2013) – 80 kW

The first battery-hybrid vessel from Hvide Sande Shipyard was delivered in 2013 for the Strynø ferry, which is based in southern Denmark. The aim was to have only two main diesel engines that were optimised for the most efficient fuel consumption. These were connected to two shaft generators which were able to operate bow thrusters and hotel loads, as well as charge two small battery banks. These battery banks power the vessel during short harbour stays when there is no shore connection or the diesel engines are not running. The engines are stopped immediately after the kingpin from the ramp is locked in the ferry.

This project provided us with valuable learning opportunities and insights, and we collaborated closely with the crew and their consultant, OSK Shiptech, to make adjustments. However, the project was ultimately successful and continues to operate based on the principles established at the outset.

We have learned a great deal about building hybrid vessels and have decided to strive to become one of the leading shipyards in the field of hybrid and battery technology, playing our part in the sustainable green transition in the marine industry.

OV Bøkfjord (2016) – 850 kW

In 2014, we won the contract for a 44-metre multipurpose vessel for oil spill operations, buoy laying and lighthouse tendering for Kystverket in Norway. The tender was a design competition to fulfil Kystverket’s requirements. Based on our experience with the Danish boy-laying vessel Poul Løvenørn, we proposed a diesel-electric design in collaboration with the naval architects A/S Jørgen Pedersen (now OSK Shiptech), which would allow the use of diesel engines depending on operational conditions. During the project, Kystverket’s management decided to start transitioning their fleet to be more sustainable and environmentally friendly, and we were asked to provide a quote for upgrading the project to include a battery bank to optimise the operational profile. In collaboration with Rolls-Royce Marine, we secured the contract to upgrade the project. The result was a diesel-electric battery hybrid propulsion system comprising 3 MW e-motors and an 850 kW/h battery bank — the largest in a commercial vessel at the time.

Throughout the project, we underwent a steep learning curve in terms of risk assessments relating to the rules for equivalent propulsion solutions, in collaboration with DNV and the Norwegian Maritime Authorities.

In 2016, we won the Danish Ship of the Year Award for this project.

Lessons learned from these two projects formed the basis for the next five projects, in which we developed routines and optimised design, approval and installation processes in collaboration with our shipyard’s closest partners in the supply chain. Our project department decided to acquire this knowledge so that we could combine different market components for specific projects.

Grotte – the Fanø ferry (2021) – 1107 kW

In 2019, Molslinjen asked us to provide a quote for the conversion of their two 50-metre sister ferries for the Danish island of Fanø. The cost of the complete conversions and life extension would be equivalent to nearly one third of the price of a new sister ferry. In the late summer of 2021, we built Denmark’s first commercially sold and driven full-electric ferry. However, in close cooperation with a professional ferry operator such as Molslinjen, we decided to install a diesel backup generator below deck. This decision was taken for the following reasons:

• Super high focus on operational reliability. If the power grid fails, the vessel can still operate by running the small generator continuously.
• No spare batteries were purchased for the project, enabling us to build a lighter vessel, save money and lithium, reduce our environmental footprint during decommissioning, and still operate the route fully electrically.

The ferry departs every 20 minutes on a 12-minute route with an 8-minute stay in port. The ferry can only charge at the Esbjerg side using a 2.7 MW charging robot. In app. 6.5 minutes of efficient charging time, the vessel can charge enough to complete two tours.

Tranen – Hjejleselskabet (2021) – 80kW

We have also completely rebuilt one of the historic passenger vessels from the famous Danish shipping company, Hjejlerederiet, in Silkeborg. We have fitted it with electric propulsion to ensure silent sailing on the beautiful lakes around Silkeborg.