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With rising fuel costs and today's global interest on emission reduction, liquefied natural gas (LNG) is considered a promising alternative fuel for all type of ships. In response to the industry's need for technical guidance for new construction and existing vessel conversion, leading classification society the American Bureau of Shipping (ABS) has announced the release of its Guide for Propulsion and Auxiliary Systems for Gas Fuelled Ships.

The new ABS guide provides criteria for the arrangements, construction, installation and operation of machinery components and systems for vessels fueled by natural gas. The objective of the guidance is to minimize operating risks and promote the protection of the vessel, its crew and the environment.

Christopher J. Wiernicki, ABS CEO and President says the shipping industry needs to examine the issues surrounding the transition from traditional fuels to LNG, to verify that solutions provide an equivalent level of safety and reliability to those established for LNG storage and transportation. "With ship operators facing economic pressures from fuel costs combined with impending regulations aimed at reducing exhaust gas emissions, particularly for sulfur oxide (SOx), LNG fueled propulsion systems could be a practical and beneficial solution. It is a matter of when, not if, LNG will be a commonly-selected fuel source and we need a sound basis for ship designs," said Wiernicki.

More than 50 years of ABS' experience with the handling and storage of LNG on board ships, many with dual-fuel diesel propulsion plants, was incorporated into the guide. Consideration was also given to industry standards including the IMO Resolution MSC.285(86) Interim Guidelines on Safety for Natural Gas-Fuelled Engine Installations in Ships, the International Gas Carrier Code and the IMO International Code of Safety for Gas-Fuelled Ships, currently under development.

Significant contributions to the Guide also came from a joint research project with DSME and A.P. Moller Maersk to develop a LNG-fuelled containership. Concluded earlier this year, the project addressed the design and technical issues surrounding the use of a 7,000 TEU containership burning LNG as fuel for both propulsion and power generation, with ABS providing Approval in Principle for the resulting design. The study also assessed operational, economic and regulatory impacts from the use of LNG as a fuel source.

Results from the study were presented by DSME in March during the Gastech conferent in Amsterdam. Found to be of particular interest were the considerations given to the type and arrangement of fuel tanks used to provide the utmost safety for the crew and to minimize capacity reductions. The study found that the initial costs for LNG fueled propulsion could be recouped within a three to 10-year period, depending upon the applied LNG prices.

"Natural gas has been used as a fuel for small regional non-LNG carriers working in environmentally sensitive areas," said ABS Director, Environmental Technology Yoshi Ozaki, who led ABS' involvement in the project "This study further supports technical feasibility of LNG fuel and suggests promise for a viable extended business line for LNG suppliers."