On January 1st, 2015, the levels of sulphur emissions allowed from ships in the North Sea, English Channel and the Baltic Sea region were lowered. As a result, many shipping companies are considering to switch from heavy fuel oil (HFO) to lighter diesel oil (MGO), which has a lower sulphur content. MGO is cleaner but more expensive, so shipping companies are also looking for more efficient propulsion concepts to compensate for the increased fuel costs. These can greatly improve the environmental performance of the vessels.
In the process to find an optimal powering system, a group of five companies, led by shipping company Flinter, asked TNO, a Dutch research organisation, to research and provide insights into the efficiency of ships. The goal was to find the most suitable propulsion for one of Flinter’s vessels, the Nordic Erika, given its operational profile.
The involved companies (MS Nordic Erika, Flinter Management, Alewijnse Marine Systems, Bolier and Wolfard & Wessels) are a diverse group of companies with specialist knowledge of the components of the powering system of ships. Together, these partners were searching for a method to quantify which retrofit improvement option would have the best results for the Nordic Erika. The technical and operational profile of the ship was used rather than optimizing if for a theoretically, designed condition.
Extensive research showed that the best retrofit option for the Nordic Erika to decrease fuel consumption (and therefore reducing the emissions), was by implementing changes in the way her power is regulated.
The Nordic Erika has a propeller with a controllable pitch, so the ship’s speed can be controlled both by the speed of the main engine as well as the propeller’s pitch. Research to the so-called ‘combinator curve’ of the vessel shows when the combination of the engine speed (RPM) and propeller pitch minimizes the fuel consumption per nautical mile.
The first step involved the companies creating a list of suitable propulsion options that could be implemented on the Nordic Erika at an initial workshop. TNO then quantified the effects of these improvement options with their in-house software tool (General Energy Systems or GES), and determined the effectiveness and the specifications for the Nordic Erika.
Then, using the ship’s data, TNO performed a search to find the most optimal combinatory curve. By using the GES simulation tool, a curve was found were the fuel consumption per mile is at a minimum for every ship speed, engine speed and propeller pitch.
By performing a “virtual voyage”, the reduction of the fuel consumption and emissions were computed. Three recent trips of the Nordic Erika were analyzed, and the speed distribution over these trips was created to find a realistic virtual voyage. The virtual voyages were performed by using real-time ship positioning (AIS) data. Based on the occurrence of a certain speed and the fuel consumption at that speed, the total consumption for the trip could be calculated. Based on these insights, advice was given on the optimal combination of engine speed and propeller pitch.
This approach and the resulting advice presented very good results for fuel economy, varying from 9% to 25% fuel savings. The fuel savings are also related to ship speed: the lower the speed, the more effect on fuel saving: (varying from 9% at 11 knots to around 25% at 9 knots).
As a shipping operator, Flinter, is enthusiastic on the savings achieved and is looking to implement the methodology for the other ships in their fleet.
One-size-fits-all solutions do not exist in maritime shipping because the operational profile (route, speed, average length of trip) and technical characteristics of ships (type of cargo, size of vessel and engine) differ significantly. To allow more vessels to achieve significant fuel savings, the approach used will be scaled up in a second phase.
A common data platform will be created where data on different ships are combined with AIS data, by Flinter and other partners. The platform will be open source in order for different companies to use their own data visualization solutions or to link them to different modeling tools.
The applied methodology for this initiative can also be applied in other fields. First selecting the most suitable options based on a preliminary model calculation, and then doing a further refinement of the most suitable option is not specific to maritime transport. Furthermore, the initiative made smart use of models and data such as AIS to apply the solutions in real time, which could also be done in road transport (with GPS data).
TNO factsheet Energyship (https://www.tno.nl/nl/over-tno/nieuws/2015/9/varen-met-energieschip-bespaart-20-brandstof)
Europe, Mitigation, Technology, Partnerships, Freight, Shipping
Bart Otto, CEO Flinter & Dan Veen, TNO Martitime & offshore firstname.lastname@example.org
“Sailing the vessel with the new combinator curve clearly resulted in a large saving reaching up to 20% whilst the same speed was maintained. It means up to 2 tons per day less fuel, and at lower sailing speeds the savings become even larger. A significant saving like this is not only welcome, it is revolutionary!“
-Bart Otto, CEO Flinter