Page 18: of Maritime Reporter Magazine (February 2, 2005)

Dawn of a New Era

By David Tinsley, Technical Editor

As the final bastion of steam turbine propulsion in mercantile shipping, the boom in the LNG carrier sector has not only given a fillip to the Japanese pro- ducers of such specialist plant, but has also sparked the uptake of alternative powering solutions. The recent entry into service of the first LNG tanker installed with a dual-fuel electric propulsion system, and the nomination of the concept for a clutch of subse- quently-contracted, larger gas carriers, are likely to have forever altered the established order in deepsea LNG carri- er powering.

Furthermore, the planned adoption of electronically-controlled, two-stroke diesel engines and onboard reliquefac- tion plant for a series of newbuilds in the 210,000/215,000-cu. m. range, the largest LNG tankers booked to date, has given added dimension to the industry's shift from traditional powering arrange- ments.

Whether or not the gas turbine will find favor in future LNGC projects, either in gas turbo-electric or mechani- cal drive layouts, or in a combined sys- tem akin to that used on a number of cruise ships, remains to be seen. The present climate of change and opportu- nity, and a new willingness to embrace innovative technology that can yield long-run efficiency and operational ben- efits, must have increased the chances of a market breakthrough.

Steam turbine systems have monopo- lized large, single-screw LNG carrier propulsion over the past four decades due to factors of reliability, familiarity and the ease with which the boilers in such installations can use the gas boil- off which continuously emanates from the LNG cargo. Mitsubishi and

Kawasaki have both augmented their offering with steam turbines suited to a new generation of higher capacity

LNGCs. However, technological advances in main engines and innova- tion in propulsion systems, coupled with growing ship size and evolving trade requirements, draught limitation impli- cations for hull and propeller design, and heightened expectations as to unit cost efficiency and operating flexibility, have prompted shipowners to consider new options.

The 74,000-cu. m. Gaz de France energy, which was recently completed by Chantiers de l'Atlantique and phased into service carrying Algerian gas to

France, has opened a new technical chapter in LNG marine transportation.

She is the first LNGC to incorporate dual-fuel reciprocating engine, electric- drive system, and has also given form to

GTT's CS1 membrane cargo contain- ment technique, offering improved qual- ities and operating advantages and reduced costs compared with earlier sys- tems.

Both the propulsion concept and CSI cargo system have also been specified for two vessels of 153,500-cu. m. ordered from Chantiers de l'Atlantique.

Gaz de France energy is equipped with four six-cylinder Wärtsilä 50DF dual- fuel engines, giving a total power output of 22.8-MW, and driving gensets deliv- ering electrical energy to a pair of

Alstom propulsion motors and all other shipboard consumers. The follow-on, larger newbuilds, Provalys and Gaselys, will each have three 12-cylinder 50DF dual-fuel engines plus one six-cylinder model, giving a power concentration of 39.9-MW.

Expansion-minded BP Shipping of the

U.K. has also endorsed the dual-fuel electric drive approach in its latest stage of LNGC fleet development, entailing four 155,000-cu. m. ships from

Hyundai, with options on four further vessels of the class. Two 12-cylinder and two nine-cylinder Wärtsilä 50DF engines will provide a primary power base of 39.9-MW in each vessel. The configuration will enable various oper- ating modes to be matched in the most efficient way, catering to fully-laden powering needs, in-harbor loads, and in- ballast voyaging. The machinery maker's recent adaptation of its dual fuel technology to allow heavy fuel oil to be used in the engine's diesel mode has fur- ther enhanced fuel flexibility, and improved operators' control over run- ning costs in the face of fluctuating gas and liquid fuel prices.

The chosen design and powering arrangements promise the requisite economy and effectiveness in handling various deployments within the Atlantic basin trading sphere at service speeds up to 20-knots, and including Trinidad and

Tobago's Atlantic LNG project, and the

U.S., U.K. and Spanish traffic.

A program of eight ships of unprece- dented size to serve planned long-term shipments of gas from Qatar to the U.K. will bring direct-drive, low-speed diesel machinery, in combination with onboard reliquefaction plant technology, to bear on the LNGC market. Construction con- tracts for a quartet of 215,000-cu. m. carriers have been split between

Hyundai and Samsung, while four 210,000-cu. m. vessels are slated from

Daewoo Shipbuilding & Marine

Engineering. The fleet will be owned by two international consortia, both involv- ing Qatar Gas Transport Co, and the investment in new capacity arises from the Qatargas II LNG project of Qatar

Petroleum and ExxonMobil.

MAN B&W has confirmed that each of the Daewoo vessels will be equipped with two 6S70ME-C electronically-con- trolled engines, driving a pair of fixed 18 Maritime Reporter & Engineering News

Tanker Technology (Photo: Cour tesy of Wär tsilä)

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