Dual-fuel marine diesel engines are increasingly being fitted to new-buildings where twin benefits of negligible noxious gas emissions (thanks to squeaky-clean combustion) and economical performance come to bear when the engine operates in LNG mode. Indeed analysts are agreed that it is only the sparse availability of LNG bunkering facilities world-wide that limits installation of far greater numbers of dual-fuel systems at a time when prices for oil fuels are uncertain, and when environmental regulations are becoming increasingly stringent.
For vessels with ready access to LNG as a fuel source, there has been a natural progression in the fitting of dual-fuel engines, beginning with large LNG carriers themselves using boil-off cargo gas when loaded. Now that progression has extended to include far smaller ships (with a no less an important role in drilling operations) which also have ready access to the fuel – LNG Platform Supply Vessels (PSV's).
PSV's in the Kleven Maritime Shipyard, Ulsteinvik (Courtesy of Kleven Maritime)
Dual-fuel Marine Engines – First Step Toward the LNG Fuelled Ship
A recent example of the trend came when Norwegian operators Eidesvik Offshore released news on 20, December 2010 that they had contracted with the Kleven Maritime Shipyard in Ulsteinvik, Norway, to build their fifth dual-fuel PSV. In addition to the all-in design of the vessel, including the hull form in conjunction with Eidesvik's in-house project team, Wartsila will supply the dual-fuel main engines and generating sets (Wartsila 20DF and 34DF respectively). The widened scope of the engine manufacturer's design compass in this order may indicate an emerging trend in the supply of dual-fuel propulsion systems, where location and construction of LNG fuel tanks must figure high on the design agenda.
LNG As Single Fuel Source – Viking Line Order
The actual construction of a large ship powered by LNG as the sole fuel source is only as far off as 2013, as Keith Henderson reported in these columns last week in a comprehensive article‚ 'World's largest LNG fuelled passenger ship', that drew attention to a contract between Viking Line ABP and the STX Finland shipyard to build a 57,000 gt passenger and vehicle ferry to be fuelled exclusively by LNG.
This new ship, now in the design stage, will link the ports of Turku, Finland and Stockholm, Sweden, a route within a Tier lll NECA (Noxious Emissions Control Area) which may lead to LNG becoming the fuel of choice by ferry operators trading within NECA's elsewhere and who must certainly be watching Viking Line's LNG innovation with considerable interest.