ClassNK’s revised edition of ‘Guidelines for Ships Using Alternative Fuels’

ClassNK has revised the safety requirements for ships using methanol/ethanol and hydrogen as fuel within the ‘Guidelines for Ships Using Alternative Fuels (Edition 3.1).’ The update is designed to enable the rational design and development of alternative-fuelled ships in line with international standards.

In Part D, covering hydrogen-fuelled ships, the revision incorporates the IMO’s Interim Guidelines for the Safety of Ships Using Hydrogen as Fuel (MSC.1/Circ.1701), issued this year, and additionally introduces a hydrogen leak frequency table that can be used for the safety assessments required under the IMO guidelines. In Part A, covering methanol/ethanol-fueled ships, new structural strength requirements for methanol/ethanol fuel tanks, not addressed in the IMO guidelines, have been established. Through this revision, shipyards, designers and shipowners can carry out design and safety assessments in line with the latest international standards, using ClassNK’s own leak frequency estimates and the relevant requirements to develop alternative-fueled ships more rationally.

As the building of alternative-fueled ships advances in response to the global challenge of reducing GHG emissions, ClassNK has comprehensively compiled the safety requirements for ships using methanol, ethanol, LPG, ammonia and hydrogen, fuels regarded as promising alternatives, into the guidelines. Taking into account the risks that the use of alternative fuels poses to the environment, seafarers and ships, the guidelines set out requirements for equipment, controls and safety devices to minimize such risks. ClassNK participated as a member of the Japanese delegation to the IMO Sub-Committee CCC 11 and contributed to the discussions in the development of the IMO hydrogen guidelines now reflected in Part D.

For hydrogen-fuelled ships, the relevant IMO guidelines have been incorporated in a full-scale revision, with a Bayesian method applied to derive estimated hydrogen leak frequencies for ships, added as Appendix 2 to Part D, enabling ship designs and their safety assessments to be conducted in a more rational and reliable manner. For methanol/ethanol-fuelled ships, structural strength requirements for fuel tanks, based on ClassNK’s experience in design review, have been developed and standardised, enabling more efficient tank design assessments.

As a third-party certification body, ClassNK said it will continue to support efforts to address environmental challenges through the development of standards, certification and the provision of information.