Long battery life
The vessels are designed to operate for sixteen hours per day and be charged two times an hour. For those readers not up to speed with battery technology, this considerable amount of charging calls for a battery with a long lifespan. “We have selected a high-end lithium battery with a long lifespan,” notes Jan. “They are quite heavy, but they do have the required longevity.” Charging takes place using two >600 kw connection chargers contained within a pontoon at shoreside.
Although the repetitive nature of public transport typically allows energy requirements to be accurately calculated in advance, Jan goes on to say that one particular aspect of the Electric Waterbus design was not so straightforward to predict. “HVAC [Heating, Ventilation and Air Conditioning] is a large energy consumer, but demand fluctuates seasonally. Therefore, the question that we needed to answer was: do we want to power HVAC capacity from the batteries? Or do we want to include another power source?”
One of the first options that was considered was heat pumps. This was quickly side-lined due to the fact that these are quite limited when it comes to water temperature. “This led us to the solution of dedicated seat heating and cooling, instead of concentrating on handling the entire vessel. At the moment, this is still in the engineering stage, but it’s very promising. It is a very efficient process as there is no waste because you apply heating and cooling only when required.”
Electric without compromise
Damen has used the ferry service running between Central Rotterdam and the neighbouring city of Dordrecht to present a proposed operational profile of a fully electric service. Here, as Jan explains, providing a realistic alternative to current diesel-powered vessels was vital. “You won’t be able to get an electric waterbus to market if it causes long delays to an operator’s schedule. We had to solve that by adding more charging power,” he says.
This in addition to the extra infrastructure required to operate an all-electric service does, of course, require considerable initial capital outlay.
“However, we can demonstrate that, looking over a twelve-year period there are huge savings to be made.”
And with this final statement, Damen is adding two further benefits to its already proven Waterbus design; decreased operational costs and zero carbon emissions.
Damen Passenger Ferries
Damen Research & Development
Damen Electric Vessels