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Tests reveal wind propulsion fuel savings on Viking Grace

Mon 20 May 2019 by Rebecca Moore

Tests reveal wind propulsion fuel savings on <i>Viking Grace</i>
Norsepower’s rotor sail on Viking Grace has created long-term fuel savings, independent tests reveal

Viking Grace’s fuel savings due to using wind energy propulsion is expected to hit up to 300 tonnes annually, independent test results have revealed.

Viking Line installed Norsepower’s Rotor Sail technology on to its cruise ferry Viking Grace. A statement explained that when looking at fuel consumption alone over the measurement period, the savings were not immediately evident. However, when NAPA and ABB reviewed the data, they were able to isolate an evident change in the propulsion power breakdown of Viking Grace, caused by the Rotor Sail. The same conclusion was confirmed with a strain gauge analysis, where forward thrust of the Rotor Sail was measured and converted into propulsion power.

Based on the different analysis, the expected long-term change in Viking Grace's annual fuel consumption due to the Rotor Sail has been verified to be between 231 and 315 tonnes on annual basis, equalling an average propulsion power between 207 kW and 282 kW.

According to the analysis results, the Rotor Sail delivers more forward thrust on the open sea legs of the route for Viking Grace, but due to the route being located mostly in the archipelago, the annual fuel savings potential is on the same level within both route areas.

As a result, Viking Line and Norsepower have agreed to continue collaboratively using and optimising the Rotor Sail on Viking Grace with the technology now fully operational. The Rotor Sail is also being deployed on Viking Line's newbuild, currently being constructed in China. 

Norsepower chief executive Tuomas Riski comments “When the test period began, we had some challenges with our new product, but were able to fix them quickly, and since the end of September 2018, the technical availability of the Rotor Sail has been around 97%. We are pleased to see that independent testing from respected, independent companies NAPA and ABB has shown impressive fuel savings potential on Viking Grace. This project has confirmed that our technology works with high-speed cruise ferries and that favourable results can be achieved with a service speed of 21 knots. During the last year we have been using the Rotor Sails in extreme weather conditions including icing events and high wind speeds, in which the Rotor Sail has been operational. Based on the harsh weather experiences so far, the Rotor Sail can be operated year-round without any weather-related issues.”

Commenting on the trials, Viking Line chief executive Jan Hanses says “…We want to pioneer the use of solutions that reduce the environmental load. Viking Line has been testing the Rotor Sail on Viking Grace for a year now, and together with Norsepower we will continue testing and optimising the sail for its current route. We are proud to be the first in the world to trial Norsepower’s world-class mechanical rotor sail solution on a cruise ferry.”

“Besides optimising operations through improved energy efficiency on board Viking Grace, the data collected by ABB Ability Marine Advisory System OCTOPUS was used to calculate the savings gained from the Rotor Sail without disturbing operations,” said ABB Marine & Ports head of passenger vessel segment at Marcus Högblom.

NAPA data scientist Jaakko Talonen said “In the actual navigational conditions there is always variation in the environment, which has an important effect on the fuel consumption. This is why a statistical regression model was applied, to overcome the variations in the comparison conditions and to disclose the effect of the rotor sail.”

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