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ferry series was that each vessel should offer an 80% cut in NOx emissions relative to existing, conventionally-powered tonnage. Gas fuelling was favoured as it promised a complete absence of smoke at any load, very low NOx, a virtual absence of SOx, and the lowest CO2


emissions


of any fossil fuel. Home-grown, Bergen lean-burn, spark-ignition gas engine technology developed and refined over two decades provided a solid basis from which to encourage the adoption of effective and efficient new propulsion arrangements. Gas-electric propulsion technology is


also central to a subsequent stage in the modernisation of Norway’s extensive fleet of fjord ferries. Under the current project, three 49.9m newbuilds entrusted to Aker Yards’ Lorient facility in France will be used by Tide Sjø to maintain inner Oslofjord routes. Norway is seeking to extend the


application of gas as a shipboard fuel through a research project designated BigLNG. The study is led by research institute Marintek in conjunction with ship operators Seatrans and Color Line, and the partners are tasked with preparing LNG propulsion concepts for shortsea ro-ro freight vessels and ro-pax ferries. Among the technical challenges presented by LNG-fuelled vessels is the comparatively high volume that has to be allowed for bunkers, impacting on space utilisation within a given hull envelope and on the endurance factor. A recent entrant to the Norwegian


offshore support vessel fleet, District Offshore’s Viking Queen, combines the merits of LNG-fuelled main machinery with the sea-worthiness properties of the Gass-Avant concept. This sophisticated offshore support vessel draws on Eidesvik’s experience with the Viking Energy, which was the world’s first supply ship to use LNG-burning main engines, and with the Viking Avant, the 1997-delivered embodiment of Vik-Sandvik’s VS493 platform supply vessel design.


Fuel cell advances One of the distinguishing features of the Avant generation is the aft location of the superstructure, a departure from usual supply ship practice. Innovation


in powering


and consideration of


environmental issues has gone a stage further in the latest ship, Viking Queen, in that provision has been made for incorporating a containerised fuel cell unit as well as the dual-fuel main power plant.


The 330kW molten carbonate fuel cell


(MCFC) will be tested during the course of the vessel’s normal operating pattern under the auspices of the FellowSHIP joint industry research project. The fuel cell is currently the subject of land-based trials, and is due to be placed aboard Viking Queen next year. MTU CFC, one of


FellowSHIP initiative, is providing a proprietary Hot Module fuel cell stack for the supply ship installation. In addition to being used in the main engines, LNG will be the fuel feedstock for the fuel cell. Electrical energy derived from the


fuel cell plant will be used for auxiliary needs. It is anticipated that the power unit will demonstrate substantially reduced emissions relative to conventional engines,


“The country’s considerable fishing fleet is estimated to account for about one-third of all emissions from Iceland, giving added impetus to the rationale for the move to hydrogen use.”


along with high efficiency, reduced unit running costs, and quiet operation. In such a fuel cell stack, incoming LNG fuel is fed to the vertical flow channels of the anodes by means of a gas distribution device. At a temperature of about 650°C, the natural gas and steam split off the hydrogen needed on the anodes, in the


Ship & Boat International November/December 2008


New hydrogen fuelling station on the Hamburg waterway system (credit: Linde Gas).


process of internal reforming. Netherlands-based design firm


the partners in the Eureka-funded


WorldWise Marine has developed a new concept of hydrogen-fuelled tug in cooperation with two Dutch fleet operators, Smit and Iskes. The proposed Hydrogen Hybrid Harbour Tug (HHHT), offering a bollard pull of 50t, would be powered by a combination of fuel cells, batteries and high-speed diesel generator sets. The hybrid arrangements are a pragmatic solution to the aim to achieve minimal emissions, since the most environmentally-friendly course of action, an all-electric plant, would not be able to deliver the requisite power for shiphandling operations.


Power usage The fuel cells and batteries combined are dimensioned to provide sufficient power for the tug when on standby and during mobilisation and demobilisation periods. Only when substantial bollard pull is required for ship-assist duties, notably when berthing a vessel, would the diesel gensets be brought into use. For mobilisation and demobilisation, propulsion would be achieved using a retractable, 300kW Voith unit in the bow,


running on hydrogen-fuelled


electric power. Since a tug spends a relatively


small proportion of her time in actual shiphandling operations, it is estimated that the HHHT would employ fuel cell power for about 85% of the time, when no harmful air emissions would be engendered. Moreover, multiple gensets are envisaged, so that the number of engines run can be closely matched to power needs at any time, to the further benefit of fuel consumption and emissions.


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