Stavangerfjord/Bergensfjord ferry profile
Fjord Line’s new twin vessels are said to have the largest LNG tanks and engines ever installed on a passenger ferry. But there were twists and turns along their construction path that needed to be negotiated
[diesel and LNG] but with pure LNG the engine does not lose any energy efficiency,” explained BGF director of sales and marketing Arild Kalkvik. Indeed, the new engines and propeller drive system will allow fuel savings of up to eight per cent. The original engines provided by MAN were removed and
FJORD LINE’S new twin vessels Stavangerfjord and Bergensfjord are said to have the largest pure LNG tanks and engines ever installed on a passenger ferry. But the building process of the two ropax ferries – which
will cover routes between Norway and Denmark - has not been straightforward. The vessels were originally designed for diesel engines, with the option to retrofit to dual fuel, but two years after Norwegian shipyard Bergen Group Fosen (BGF) started constructing them, Fjord Line decided to switch to pure LNG. The decision was made on the back of several factors, including that the delivery of the 7,000 tonne hulls were delayed from Stocznia Gdansk shipyard in Poland, which created the time needed to assemble the new LNG engines. Furthermore, fitting the LNG engines now meant that
the vessels would be ready to meet the new 0.1 per cent sulphur regulations before they came into force in 2015 and so avoid having to be taken out of service for three months to be retrofitted with LNG or dual fuel tanks once the law was enforced. This means that Fjord Line will “achieve the regularity we have been working towards without a long service interruption in 2014,” Fjord Line chief executive officer Ingvald Fardal said. As well as containing no sulphur, the use of LNG reduces
CO2 emissions by 20-30 per cent and emissions of NOx by around 90 per cent compared to heavy fuel oil.
There was also cash support: the Norwegian ferry
operator had financial help from the Norwegian NOX fund – to the tune of €12 million (US$16 million) per vessel – and €9 million (US$11.6 million) from the EU Marco Polo fund as incentives to fit the more expensive, but more environmentally friendly LNG engines. Mr Fardal commented at the time: “We are very pleased to have signed agreements to ensure our ships will operate in the most environmentally friendly way and on commercially attractive terms. At this time we would like to thank the NOx Fund for the contribution that made this possible.” In addition to meeting the 2015 sulphur regulations and being environmentally cleaner than dual fuel, there is the added advantage that LNG engines are more energy-efficient than dual fuel engines, so save more money in the long run. “The benefit of using an LNG engine rather than dual fuel is that, with the latter, you lose 10 per cent of the engine’s power, as it is a compromise between two different worlds
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are currently on sale. Rolls-Royce was selected to provide the whole LNG package: four BERGEN BV12PG engines rated at 5,6MW each, engines for each ship that provide a total power output of 22,000kW and two x 296cbm LNG tanks with ACON-Gas control system and a Promas integrated rudder and propeller propulsion system, including thrusters, steering gear and stabiliser fins. The LNG engines provided are produced by Bergen Engines – a 50/50 joint venture company between Rolls-Royce and Daimler. Fjord Line technical and nautical director Morten Larsen explained that the manufacturer was chosen because its gas engines were “well proved”. Indeed, Rolls-Royce pointed out that the performance of its LNG package had been proved as it had been used on other ferries that manoeuver in and out of highly congested ports. BGF project manager Håvard Larsen explained that “to
fit four engines and two 175-tonne LNG tanks into a finished hull was very demanding.” This was especially the case as the tanks are larger than the original tanks and there were only a few centimetres of clearance. Parts of the ship’s hull had to be cut out to make space for the tanks, with the four new engines being fitted through the lower car deck. There were other challenges too. “The pipes were made for diesel engines and to change to an LNG system meant that a lot of them had to be replaced and changed,” Mr Larsen said. The use of LNG had the added bonus of allowing a waste heat recovery system to be fitted to generate energy for the hotel and public area due to the engines’ generation of exhaust temperatures of above 450°C. The dual fuel/diesel engines options would not have generated temperatures high enough to enable this to take place, Mr Larsen said, singling this out as one of the most innovative aspects of the twin ships. “It would be a huge loss and a waste to just dump the heat generated into the air, which is why we decided to use it for a waste heat recovery system that is of such a level that we cover the full requirement of accommodation and public spaces.”
This in itself was a challenge as Mr Larsen explained:
“We saw the benefits of the system when we had the luxury of the LNG approach but we did not plan for this at all originally, so had to come up with a solution of how to install the system.” The major benefit of recovering waste heat from the main engines is that it will save up to five per cent in fuel. Aalborg, an Alfa Laval company that has enjoyed a long partnership with BGF, provided the waste heat recovery
STAVANGERFJORD/BERGENSFJORD Length oa
Breadth moulded Draught, design Deadweight Passengers Crew Flag
Class
170m 27.5m 6.35m
3,900 tonnes
1,200 (1,500 during the summer) 100
Denmark Det Norske Veritas
Passenger Ship Technology I 2nd Quarter 2013 I 19
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