MODULARITY FOCUS about swapping out the onboard kit if another solution appears more appropriate? After all, a defined output within a particular footprint appears supremely well-matched to a ‘plug-and-play’ approach. DNV GL’s laboratory ship concept does just that. Envisioned as a vessel to test, qualify and benchmark new maritime technologies, Experior is designed to be flexible in terms of interchanging onboard components and systems. Therefore, it holds the potential for interrogating a vast array of alternatives, from superstructure and cabins to power and manoeuvring kit, to comms and control, mostly by sitting them in dedicated containers with monitored interfaces. Although not a commercial vessel, the ideas behind Experior may hold a clue to the future: its set up allows clients to calibrate and optimise their own innovations against the lab ship’s digital twin before installation. ANALYSIS In fact, according to Knutsen, a digital twin may be part of a modular delivery, allowing systems to be pretested in the factory. There’s a further advantage. “So far full vessel reliability modelling has been challenging,” he says. However, since each module will have a health check element, it’s possible to network these together, creating a “system of systems”. It would, he remarks, gradually build up over time, being far less costly and troublesome to implement than dropping an entirely new, ship-wide layer into place. It may also help resolve another niggling issue: cybersecurity. There’s often persistent doubt that the vessel’s onboard systems are as watertight as the hull, so modularity should provide more reassurance - firstly, it could potentially reduce shared weak points, secondly it “ensures that software systems are always up to date and robust in the face of challenges”, says Sverre Torben of Kongsberg Maritime Digital. COMPLEXITY However, the MIDAS project has shown there are a few knotty issues to overcome - not all purely technical in nature. Knutsen explains: “You can create a health indicator for a bearing with no problem, but doing the same for the power management involves thousands of signals. If the manufacturers are tasked with keeping their modules running, they will need to be able to pull the data out in the same way from any ship.” And, he adds, without it being “the labour-intensive process” it is at present. It’s not just the OEMs: the information will have to be shared with owner, systems integrators and last but not least, the classification societies. As Knutsen underlines, “there are more than 10,000 ships on DNV GL’s books so we’ll need a good, sanitized way of sorting it all out”. Although there is “some movement” toward developing an industry-wide ISO standard, he admits rather than trying to make existing arrangements line up, it’s far easier to accomplish coherency on a newbuild where a useable format can be implemented from the very start. SAFETY Any module worth its salt would need to cover all the bases: “Besides the monitoring, maintenance plans, approvals and so on, it would need to include designed-in safety systems,” points out Knutsen. The latter presents its own challenges as its characteristics change with the fuel. Take LPG, he says: “It’s heavier than air, so standard gas detection equipment in the ceiling won’t work.” Further, while modularity relies on a set of discrete systems, safety kit appears to pull in the other direction.
Ammonia, for example is toxic and corrosive, so if there’s a failure in any part of the fuel supply, the entire ship could be endangered. Therefore, these safety systems have to extend throughout the whole vessel. “There is no perfect fuel, no perfect way forward”, underlines Niclas Dahl of Alfa Laval. “They all have pros and cons: some may simply be limited in supply. Some, like ammonia, require more in handling the risks.” But he stresses, this should not stop development.
8 Modularity could provide futureproof ship design and paves the way for greater standardisation
FUELS AND ENGINES Wärtsilä has been playing with modularity for a while: Nico Höglund explains that development really picked up with the release of the Wärtsilä 31 medium-speed four-stroke: “Before that, if you wanted to change from diesel to dual fuel, you’d have to re-machine the engine block.... but the 31 makes it all much more straightforward, you basically only need to add the gas components.” It sets the scene for what lies ahead. Höglund adds: “Both methanol and ammonia are currently being evaluated as potential next-generation fuels, partly because they have the potential of being created in a completely green supply chain.” Interestingly, both can also be kept in liquid form with a modest amount of pressure and cooling. Therefore, Wärtsilä’s modular approach should enable easier conversions: “If you have a dual-fuel engine running on LNG, the installation already contains the majority of what’s required, such as the fuel storage tank,” says Höglund, although both methanol and ammonia will need modified fuel injection along with process equipment and corresponding safety systems. MANAGEMENT Despite sounding deceptively simple, these fuel changes “require very good engine management”, adds Höglund: ammonia ignites and burns differently compared to other methane fuels and likewise, methanol has a lower calorific value requiring a change to the automation software. This is central, he says: “Outside its operational parameters, the engine can start to knock or miss-ignite. The engine’s automation system has to take action to ensure proper combustion in order to avoid a potential escalation of the situation, which could lead to shutdown. So it’s not just about optimising performance, it’s also about safety.” Moreover Alex Grasman of MARIN points out: “One important factor is that burning alternative fuels in a
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MAY 2020 | 11
