Different modes of transport form a lifeline for Copenhagen’s citizens. As a result, the city’s politicians wanted a greener public transport service, on water as well as on the road. Copenhagen’s public transport authority Movia issued a tender to upgrade the current ferry service and route to a greener alternative.
Damen Shipyards and Arriva combine their strengths
Arriva has been running this ferry service for more than fifteen years already with its existing conventional diesel-driven vessels and therefore has great experience with the route and operation.
Arriva is Europe’s largest transport provider, taking a leading stance in reducing its environmental impact, incorporating new technology as soon as it is developed to help reduce emissions.
The company’s customers are at the heart of everything it does. Arriva strives for excellent satisfaction levels and has won a UITP Transport Achievement Award for “putting people first” and improving the overall transport experience for clients, employees and customers in Copenhagen.
Damen combined strengths with Arriva in this project, using its shipbuilding knowledge, creativity and dynamism to help its client find an ecological and economical solution. The Damen E-Ferry 2306 is a customised design, specifically developed for the Movia tender in cooperation with Arriva. The design is based on Damen’s E-Cross philosophy and overall experience with providing optimal Design and proposal engineer passenger experience combined with efficient propulsion.
Arriva requested more body in the fender construction and more daylight in the cabin and wheelhouse. Damen added stronger fenders, large windows, and additional skylights to the ferries. The vessels need to be highly manoeuvrable, able to resist high winds and icy waters, so they have a low superstructure to minimise wind resistance and a strong hull, with ice strengthening in the bow.
The cabin is slightly raised and features generous windows fore and aft, and together with CCTV feeds from strategic points on the vessel, supplies optimal visibility for the captain when manoeuvring. Inside the wheelhouse, the dashboard is fitted with an optimised human machine interface (HMI), offering minimum distraction while providing the exact information needed to pilot the vessel with maximum efficiency.
Given the demands of its operation, each ferry carries two drivetrains to provide a good level of redundancy should any unexpected problems occur.
Propulsion was a major factor in the design of the vessels. Movia requested a cleaner, greener use of energy from its ferry service, and Damen had a number of options available. Engineers considered biodiesel engines, hybrid vessels with generators on board, and full electric solutions, ultimately deciding full electric was the optimal choice for the twelve year operation of the ferries, based on several factors.
This zero emissions, fully electric solution is quiet in operation and is much more maintenance-friendly than a diesel option. Combustion engines contain a lot more mechanical parts that can fail, and the oil used for lubrication of these moving parts makes the system very dirty in comparison with an electric motor.
At the same time, Damen investigated the shore solutions for supply of electric power. Movia’s stipulations required at least 60% of the power to be drawn from a green source, so Damen ensured this shore option was available for recharging purposes.
The next decision to make was how often the vessels could charge their power supply – how could the ferries operate all day on a minimal battery pack and recharge without disrupting their schedule?
To answer this question, Damen Civil – another branch of Damen’s complete service provision – investigated full civil solutions such as accessibility to the local grid, the regulations surrounding civil power supply, and the practical limitations of the jetties as potential charging points. The ferry route takes one hour to complete, and at each end there is a small window in which to prepare for the beginning of another route. Damen saw this as a window of opportunity to take advantage of a fast-charging system.
Design and proposal engineer Bastiaan Vink explains the logic; “By charging every hour, the ferries replenish their relatively small battery pack at the beginning and end of each route. The combination of a fast-charging system and a small battery pack allows them to recharge in as little as seven minutes without disrupting their schedule.”
Completing the project wasn’t as simple as putting boats in the water – meeting the tender’s criteria for an environmentally-friendly source of propulsion for the vessels raised a number of complex variables that required investigation. Martin Verstraaten, Damen sales manager, took his team to Copenhagen to get a good understanding of the full scope of the project.
"In Copenhagen, we conducted an extensive safety and reliability investigation to get an exact understanding of the conditions and requirements of the project. We made sure we were aware of every component and contingency."
Examples of these components include the floating jetties that serve each stop on the ferry route; new vessels supplied to operate the route had to be compliant with these jetties and had to account for all aspects of accessibility and safety. A more aesthetic component was Damen’s careful consideration of the passenger experience: Damen fitted large windows along the vessels’ sides, and rows of skylights in the roof, in order to allow plenty of daylight to enter the passenger hold. Each boat features unique interior décor, including an image of a local landmark, adding to its individual personality.
The hulls were designed to achieve low resistance in order to save on the energy required from the battery packs and the propeller was optimised for electrical propulsion using software that measures the torque of the engine and the speed of the propeller.
In the fully-electric solution, power comes from battery packs on board. Bastiaan Vink, design and proposal engineer at Damen, was heavily involved in the process. “Choosing the battery packs depends on multiple variables such as the length of route and time in operation, the torque of the engine and the average weight of the vessels under operational conditions.
“We used computational fluid dynamics (CFD) in the design of the hulls to ascertain the levels of resistance they would face in the water and the propulsion required to overcome the resistance to a highly mobile and manoeuvrable degree. The hulls were designed to achieve low resistance in order to save on the energy required from the battery packs and the propeller was optimised for electrical propulsion using software that measures the torque of the engine and the speed of the propeller.”
This foresight helps to minimise the number of battery packs the vessel needs to carry on its route, which in turn saves on weight and allows it to operate more efficiently, also saving on cost.
Based on large-scale, complex projects such as this, the development of Damen’s role beyond that of a shipbuilder towards that of a full solution integrator goes from strength to strength.
The charging and operation of the ferries is a total integrated solution provided by Damen. In the earlier stages of the project, Damen acted as a consultant for a full ship and shore solution to the ferry service, considering the requirements of the project and proposing a balanced solution to meet each of the criteria. Damen Civil was able to analyse the physical capabilities and limitations of Copenhagen’s jetty route in order to determine the optimal solution for the project.
As the vessels dock bow-first, engineers realised a drive-on charging system would much better suit the vessels than a connection lowered from above. In a new system developed in-house, Damen installed a charging point in the bow of the vessel and created an automated charging system based on the jetty and connected to the on-shore power source. In this system, the vessel can drive onto the charging pin bow-first, automated fast-charging replenishes the battery power in around seven minutes, and the vessel is then able to reverse straight off the pin and begin its route.
During development of the charging solution, engineers used a hardware in the loop (HIL) process to run tests on how it would perform in operation under various conditions.
The team then used software to construct a digital model of the vessel, and conducted test runs on the computer in order to tailor battery management software that keeps track of charge and release performance.
Transformer in the works
“At the point at which construction of the five vessels was almost ready to begin, a change in requirements was announced. Movia wanted to extend its ferry route by an additional four stops, increasing the length of the route by roughly 50% and taking the ferries into Copenhagen’s port area,” explains sales manager Martin. As part of the expansion, two additional vessels were requested from Damen.
“The route extension significantly impacted the scope of the project, affecting the duration of each route, the power demands on each vessel, and the charging facilities installed to supply that power. We investigated ten scenarios for a fullyintegrated solution to the route extension, ultimately deciding the project expansion required an innovative charging solution to be installed at the port area terminal,” Martin states.
Stronger weather conditions, producing a larger wave impact in the port area, affects movement of the ferries at the jetty, which must therefore be secured in order to access the charging system. Damen’s solution to this challenge was to develop an auto-mooring system that controls the motion of the vessel and secures it to the jetty as its batteries are charging. This solution largely increases the safety around the integral system.
The auto-mooring system was designed and engineered in collaboration with Damen’s Winch Department. The development of this mechanical system required the measurement of wave dynamics and calculation of the forces involved in vessel turbulence in order to produce a secure mechanism. With no pre-existing solution available on the market, the bespoke system was developed in-house by Damen and is currently being adapted for use in similar electrical propulsion projects with future clients.
In addition to the vessel security, Damen adapted the charging process to cope with the higher demands of an extended route. Damen increased the battery charging capacity from 450kW to 600kW per charger, to supply each vessel with the power it needs to complete the route – including in the case of one charging point being temporarily disabled – accounting for further redundancy in the system.
Damen will deliver the first five vessels according to contract, and the two additional vessels will be ready for delivery in May 2020. The charging point system is close to completion, and Damen looks forward to the beginning of its operation. Proud of the interdepartmental collaboration displayed throughout, Damen regards this project as an excellent showcase of its engineers’ entrepreneurial capacity and vision. “Based on large-scale, complex projects such as this, the development of Damen’s role beyond that of a shipbuilder towards that of a full solution integrator goes from strength to strength,” Martin concludes.
Looking back to the future
To enable operators to track and analyse the performance of this complex system in action, Damen can install remote monitoring capabilities on all of the vessels, informed by a network of on-board sensors. Damen’s Remote Monitoring Department is able to set up personalised dashboards for every employee, tracking a variety of factors from battery lifecycle to sailing patterns to swell dynamics. Through access to this data, clients can track the performance of their vessels. Similarly, Damen is able to use this remote monitoring capability to identify potential areas for improvement and use the data to inform future projects.
Damen Ferry 2306 E3