Norway encourages gas propulsion solutions
Norway’s environmental strategy has provided a fillip to the uptake of gas-fuelled machinery in the marine sector, writes David Tinsley.
While Mitsubishi gas engines figure in a number of Norwegian fjord ferry applications, the availability of home-grown powering solutions is benefiting the country’s own engine building industry. The Hordvikneset factory near Bergen, the fountainhead of the Rolls-Royce group’s medium-speed reciprocating engine design and production know-how, has a long track record in lean-burn gas engine technology.
Recourse to the Bergen product range is integral to a further stage in the modernisation of the Norwegian coastal ferry fleet, involving a series of 4,300gt vessels for operation in Vestfjorden, a stretch of water known for its harsh conditions. The four LNG-fuelled ferries have been ordered by Torghatten Nord from the Remontowa Group in Poland, and will be deployed on two routes serving Lofoten.
The 93m design has been developed by LMG Marin of Bergen in cooperation with Remontowa Marine Design & Consulting. Unlike the double-enders that have figured in much of the Norwegian inshore ferry fleet renewal of recent years, Torghatten’s nascent class is of more conventional form, with stern propulsion and a drive-through configuration for up to 120 cars, in addition to facilities for 390 passengers.
Each of the two ferries that will be assigned to the inner Vestfjorden route has been specified with a nine-cylinder example of the newly-developed Bergen C26:33 gas propulsion engine, rated for 2,430kW at 1,000rpm. The two other newbuilds destined to operate in the outer waters of Vestfjorden are each to be installed with a larger, medium-speed Bergen gas engine, in the shape of a 12-cylinder B35:40VPG unit, to deliver 5,250kW at 750rpm.
In addition to Bergen lean-burn gas engines and the Promas integrated propeller and rudder system, the Torghatten series will also showcase another field of Rolls-Royce technology by providing the first contract for the hybrid shaft generator (HSG) system.
The C26:33 marine gas engine, derived from the Bergen C25:33 diesel, is claimed to provide an effective powering solution for applications in areas facing especially strict environmental controls. Emission levies such as the Norwegian carbon dioxide (CO2) and oxides of nitrogen (NOx) taxes are a spur to the use of lower-pollutant alternatives to current, standard diesel plant.
Relative to engines burning liquid fuel, the natural gas-ingesting Bergen C26:33 type achieves a 92% reduction in NOx and 22% lower CO2, with negligible emissions of sulphur oxides (SOx) and particulate matter (PM). The NOx credentials of the new engine range will render installations compliant with IMO Tier 3 limits, and will meet even tougher criteria, as foreseen under a Tier 4 regime. It is claimed that the design minimises methane slip, regarded as a shortcoming of gas fuelled machinery.
The C26:33 series has initially been released in six-, eight- and nine-cylinder in-line models, covering the 1,460kW to 2,430kW power band at 900 and 1,000rpm running speeds. It is seen as the long-term successor to the K-series gas engine family, which was nominated for Fjord1’s first-generation of LNG-fuelled, gas-electric double-enders. These have been assigned to main crossings that form an integral part of the west coast highway system.
K-series gas engines have also been nominated for two short-sea ro-ro freight vessels ordered by Sea-Cargo at India’s Bharati Shipyard.
Among the key practical merits of the new C26:33 design, as with established models in the Rolls-Royce Bergen gas engine portfolio, is its suitability both to constant-speed genset drive and to variable-speed mechanical power transmission to a controllable pitch propeller. By contrast, some gas engines are less able to cope with the load and speed variations entailed in direct propeller drive.
The first production engine of the C26:33 type entered service at the beginning of 2011 as a retrofit installation in the Norwegian double-ended ferry Tresfjord. Built in 1991 with a diesel-electric installation founded on a Bergen BRM-6 diesel engine, the conversion of the 97m long ferry to employ a gas-electric solution was precipitated by owner Fjord1 MRF’s landing of the concession to operate a route across Trondheimsfjord for eight years using three gas-fuelled ferries, including Tresfjord.
The existing BRM-6 diesel and generator were retained, along with the cp propeller-equipped thrusters at each end of the vessel. The new, nine-cylinder C26:33L9A gas engine was fitted to drive the generator from the opposite end to the diesel engine. A clutch in both the existing and new drivelines allows either engine to power the generator, although only one engine is coupled at any given time. On its new route, and in normal circumstances, the ferry will only use LNG as fuel, drawn from an insulated tank and vaporised into low pressure gas to feed the engine.
In the largest vessel application to date for Bergen gas engines, three C25:33L9A nine-cylinder units have been ordered for a gas-electric double-ender ordered by Fjord1. The ferry will be capable of making more than 20 knots, carrying up to 600 passengers and 242 cars. The vessel will primarily serve the Arsvaagen/Mortavika crossing on the highway route between Bergen and Stavanger, and has been contracted from Western Shipyard in Lithuania.
Two further engines of the new series will be used in the gas-electric/diesel-electric propulsion system of each of two UT776-type platform supply vessel to be built for Island Offshore, a champion of Norwegian technical and design innovation. In addition, a six-cylinder C26:33 gas engine will power a new Norwegian coastal vessel to be used in fish farm logistics(see below).
Rolls-Royce is set to further augment its portfolio with an in-line version of the Bergen B35:40 gas engine, currently available in vee-form configurations.
An innovative vessel designed to carry feed to fish farms along the Norwegian coast has been specified with gas propulsion to fulfil the charterer’s requirements as to both fuel efficiency and low environmental footprint. A mechanical drive train will be employed with the gas engine.
The 70m-long coaster has been ordered from the Tersan Shipyard in Turkey by NSK Shipping on the strength of a long-term charter from BioMar, a supplier of fish feed to the aquaculture industry. The vessel has been developed by the owner’s design bureau Nordnorsk Skipskonsult, and Det Norske Veritas has provided input on technical issues. Rolls-Royce has been entrusted with the supply of the complete propulsion system, including gas engine, gas handling system, shaft generator and automation.
Although the adoption of an LNG-fuelled solution entails an estimated, overall added capital cost for the ship of NOK28 million, according to DNV it is reckoned that backing from Norway’s NOx Fund, given the ship’s very low NOx emissions, will cover NOK18 million of this additional expenditure.
NSK’s specialised vessel, embodying a forward superstructure and laterally-mounted deck craneage, has been arranged to transport about 2,000 tonnes of fish food pellets, which will be transferred pneumatically to each farm’s storage pontoons. The prime mover will be a six-cylinder gas engine of the Bergen C26:33 series, rated at 1,620kW and driving a Promas integrated rudder system through a reduction gear. LNG fuel will be stored in a 90m3 insulated tank.
BioMar is reportedly contemplating further investments in such capacity, to boost the efficiency of deliveries from its Karmoy and Myre factories, while meeting sustainability goals.
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