Is a 'green' tugboat a feasible option? The E3 Tug project demonstrates that it is possible to make sustainable and profitable choices in al the stages of tugboat design and development. Aided by the modelling systems of IMARES, Wageningen UR's research institute for marine ecological research.
In anticipation of increasingly stringent international environmental rules, the maritime sector has embraced sustainability. One of the organisations at the forefront of this trend is SMIT, an internationally active maritime service provider based in Rotterdam. SMIT took a closer look at the 'powerhouse' of the fleet: the harbour tug. The engine power of a tug is adjusted to the maximum tensile force required during in-port operations, and according to Jules Verlinden, Innovation Coordinator at SMIT, this is where improvements can be made. "Tugs only run at maximum capacity during a small fraction of the total tug time. During the remaining time the big diesel engines are on standby, or are running at low capacity. "
Total environmental impact
SMIT contacted Damen Shipyards and ship builder Alewijnse, a specialist in marine electrical engineering. The aim of the collaboration was to develop a tugboat which emits less harmful substances, is cost-effective and efficient at the same time (the abbreviation E3 stands for Economically viable, Environmentally Friendly and Efficient in operation). The most challenging part was that a reduction of one emission can lead to an increase of another. This is why the the project focused on the impact of emissions on the local and global environment, rather than on reducing absolute emissions. Some emissions, such as NOx, mainly impact the environment in and around the port, whilst emissions such as CO2 influence the global environment.
Environmental Impact Factor
The collaborating organisations sought a method with which they could map the design modifications that would be most beneficial to the environment. Verlinden: "The methodology also had to take changing conditions in the world into account. It turned out that IMARES had the right expertise for the job.”Based on methodology IMARES already applied in the oil and gas industry, the institute developed a modelling tool to calculate the Environmental Impact Factor of a tug. Verlinden: “You can see the local and global environmental impact of each improvement. The goal of this project was to maximise environmental benefit. But because we had another model with which we could calculate the costs of these improvements, it was possible to 'play' with the design: which improvements have the most effect under certain circumstances?”
The E3 Tug project has now been completed. It has provided SMIT and the other partners with a lot of knowledge. Verlinden: “The project has resulted in what we had expected: a model that predicts the environmental impact of tugboats and which can be applied in different contexts and all over the world. Moreover, it is a model which we can apply in a broader context. We currently only focus on emissions into the atmosphere, but in the future we can also use it to analyse the environmental impact tugs have on water (for example ballast water). We can also advise our customers and partners about the measures they can take to reduce environmental impact. We enjoyed working with IMARES, and our cooperation will undoubtedly be continued.”