Japanese classification society ClassNK said on Tuesday it had revised its safety guidelines for ships using alternative fuels, incorporating new international requirements for hydrogen and introducing new standards for methanol- and ethanol-fuelled vessels.
The revised "Guidelines for Ships Using Alternative Fuels Edition 3.1" are designed to help shipyards, designers and shipowners conduct safety assessments and develop alternative-fuelled ships in line with the latest international standards.
ClassNK said the update comes as the shipping industry accelerates efforts to cut greenhouse gas emissions and explores alternatives to conventional marine fuels.
For hydrogen-fuelled ships, ClassNK has incorporated the International Maritime Organization's Interim Guidelines for the Safety of Ships Using Hydrogen as Fuel, known as MSC.1/Circ.1701.
The classification society also added a hydrogen leak-frequency table to support safety assessments required under the IMO guidelines. It used a Bayesian statistical method to estimate hydrogen leak frequencies, similar to the approach previously applied to ammonia.
ClassNK said that the estimates are intended to help ship designers conduct more reliable risk assessments and support regulatory approval of hydrogen-fuelled vessels.
For methanol- and ethanol-fuelled ships, ClassNK introduced structural-strength requirements for fuel tanks, addressing an area not specifically covered by the relevant IMO guidelines.
The new requirements are based on ClassNK's experience reviewing the designs of methanol- and ethanol-fuelled vessels and are intended to standardize and streamline tank design assessments.
The guidelines cover safety requirements for ships using methanol, ethanol, LPG, ammonia and hydrogen, including equipment, control systems and safety devices to reduce risks to ships, crews and the environment.
The latest revision is part of efforts to provide a more consistent regulatory framework as shipowners consider alternative fuels to meet the maritime sector's emissions-reduction targets.