DNV: Safe implementation of decarbonization technologies onboard vessels

Classification society DNV on Wednesday (23 July) outlined various decarbonization technologies such as wind-assisted propulsion systems and lithium-ion batteries as well as the class notations or recommended practices that can help ensure their safe implementation: 

Safety considerations should be part of every decision to adopt a particular technology or modify a vessel. While some technical efficiency enhancements, such as propeller retrofits, passive air lubrication or hull modifications, typically do not influence the on-board routines, others, including wind-assisted propulsion systems (WAPS), shore power, battery systems, active air lubrication systems and alternative fuels, introduce risks related to structural integrity and new procedures on board or changes to existing ones, which need to be accounted for.

Furthermore, most technical modifications require class approval. DNV class notations exist for many enhancements and are mandatory if relevant measures are implemented. For major retrofitting projects, a comprehensive risk assessment is generally advisable and, in many cases, required by class or the authorities, especially where the regulatory environment is incomplete.

Safe and efficient integration of wind-assisted propulsion

WAPS change the loads acting on the vessel structure as well as the ship’s aerodynamics and manoeuvrability significantly. Furthermore, they have an impact on port operations and may interfere with overhead structures such as bridges when operating in coastal areas. Ensuring the ship’s structural fitness for WAPS and the chosen system’s robustness, reliability and operational safety in harsh marine environments is critical, requiring thorough testing.

WAPS can interfere with the line of sight and the visibility of navigation lights, and affect the radar blind sector, all of which have implications for compliance with statutory requirements. In some cases, WAPS may induce noise and vibration which can affect crew comfort and vessel integrity.

Navigating a ship with active WAPS takes experience and skill and typically requires updates to on-board practices, safety protocols, maintenance routines and equipment. Control systems for the propulsion engine and WAPS should be integrated to allow the efficient coordination of both. Comprehensive crew training is essential to ensure safe and efficient WAPS and vessel operation.

DNV rules ST-0511 define structural design loads and associated safety concepts for WAPS for designers and manufacturers. The class notation WAPS is mandatory when installing WAPS on an ocean-going vessel. DNV offers its Approval in Principle (AIP), Type Approval Design Certificate (TADC) and Type Approval Certificate (TAC) as WAPS technology qualifications.

Safety essentials for active air lubrication systems

Active air lubrication systems (ALS) on ships must meet stringent safety requirements to ensure safe and effective operation. These include approval by a classification society, structural assessments to account for hull modifications, and integration with ship stability calculations. Machinery components such as air compressors and piping must be marine-grade and equipped with overpressure protection. Continuous monitoring, automatic shutdown features and integration with the ship’s automation systems are essential for optimal performance. DNV has issued a recommended practice for establishing a standard for verification of the performance of air lubrication systems.

Note: The full article by DNV on ‘Safe implementation of decarbonization technologies’ can be read here. 

Photo credit: Alfa Laval
Published: 25 July, 2025