Hybrid ‘cookbook’ for smaller yards
The hybrid car market has taken off, so why not workboats? It’s not down to lack of interest Dennis Doerffel of UK-based REAP Systems told MJ; instead the issue centres on the individuality of the builds. And the builders.
Despite the promise of better fuel consumption and maintenance intervals plus lower emissions, noise and vibration, workboats have been slow to take up hybridisation. Why? “Its still financially risky as it’s relatively new technology,” said Dr Doerffel: “Do it right, you can make savings. Do it wrong and you won’t get a return on the investment.”
“At the moment implementing a hybrid drive train is still asking a lot. There are a hundred or more shipbuilders in the UK but most of them only have four or five permanent staff, and of course they can’t afford to have their own electronics engineers, software programmers, systems integrators and so on just to make one, specific vessel.”
Therefore the point is to “bring hybrids out of the realm of research projects and make them more like choosing a recipe from a cookbook” he explained.
“One problem so far has been that while a particular solution might be on offer, you are then tied to its manufacturer, you can’t just mix-and-match different components like a modular battery, motor, inverter, energy management, display, generator and so on.”
This kind of system would be a very different proposition: various elements from a variety of manufacturers would be selected from a list that suits the build, whether it’s a pilot boat, windfarm support craft or an inland waterway vessel – or even an entirely novel vessel.
However, owner and yard would still have the security of knowing both hardware and software would already be primed to accept that particular configuration.
Not easy. “To do this the system has to be modular, with an open architecture that allows different components to be connected whether these are fuel cells, batteries or other power sources,” explained Dr Doerffel.
In order to carry this mix and match offering forward there’s plans for a UK funded project to bring a number of partners together: there’s been a broad industry response and even a large engine manufacturer has shown an interest in the potential project. Other partners will come from academia and yet other ‘strategic’ elements will help provide a way to disseminate the ideas. However, it won’t stop with the founding group said Dr Doerfel: “As it progresses, others will join us.”
There are already some solid ideas in place: “We didn’t want to make it a series hybrid as this would entail transferring all the energy through to an electric drive,” he explained. After all, many operators want to cover longer distances at a fairly high pace; windfarm transfer vessels, dive support boats and short hop ferries all want to pick up speed once out of the harbour or fairway and so they don’t want to lose the efficiency and proven reliability of straightforward diesel.
“Therefore, what we want to do is keep the direct drive train intact with the hybrid element added to it, possibly linked via an electric motor sitting inside the flywheel.”
“Battery size is always an important topic, because while a large array usually lasts longer, this incurs both more weight and costs, so we will have to try and make it as small as possible. But there is a lot the management system can do to improve cycle life and make the most of the power density.”
“We are also looking at a DC distribution system. Frankly I have seen companies try to integrate components within an AC system and they have really struggled to keep the power at the right frequency and so on.” He added smaller vessels could take advantage of a relatively low voltage DC bus, “something in the range of 400V which will allow the current to go straight from a charger-inverter without routing through another DC to DC converter”, keeping components and consequent costs down.
A working vessel is a good choice for a testbed explained Dr Doerffel: “Many projects build from new and use up all the available budget, whereas we want to focus on one specific element, the hybrid drive. Plus, if the boat’s been running for some time there may be a lot of historical data that would give us a baseline for comparison.”
There are many potential pitfalls to bringing all this together. Every vessel is going to be different, which means each installation will need tuning to determine, for example, when the engines or batteries cut in to take the load and Dr Doerffel is aware of possibly time-consuming delays inherent in this phase:“We need to make sure this period can be restricted to days rather than months otherwise customers are going to get frustrated”.
However, if all this works, it might lead the way to a large hybrid marine ‘technology cluster’.
By Stevie Knight
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