KR (Korean Register) has granted Approval in Principle (AIP) for the ammonia-fuelled ship safety solution ‘Hi-CLEARS’ (Hyundai integrated Clean Liquid based Ammonia Release mitigation system with SCR).
The system was developed in collaboration with HD Hyundai Heavy Industries (HD HHI) and HD Korea Shipbuilding & Offshore Engineering (HD KSOE) and was announced on September 11 at Gastech 2025 in Milan, Italy.
Future international technical standards
The approval is the result of a joint development project aimed at overcoming safety and regulatory barriers
The approval is the result of a joint development project aimed at overcoming safety and regulatory barriers to the commercialisation of ammonia-fuelled vessels and at laying the groundwork for future international technical standards.
The newly developed Hi-CLEARS is a safety-enhancing system that swiftly captures any ammonia gas leaked during operation, converts it into aqueous ammonia, and uses it as a reductant in an SCR (Selective Catalytic Reduction) system.
This innovative solution not only eliminates potential ammonia leakage, but also achieves a ‘Zero Discharge’ of ammonia to the atmosphere and sea, earning recognition as a breakthrough technology.
Application of SCR systems on ships
KR took a central role in amending IACS Unified Requirement M77, which governs the application of SCR systems on ships. The revision, based on risk assessment, now permits aqueous ammonia and ammonia itself to be used as reductants, where previously their use was restricted.
This change provides the technical foundation needed for the commercialisation of Hi-CLEARS and demonstrates KR’s commitment to shaping international safety requirements.
Safety and environmental regulations
KR took a central role in amending IACS Unified Requirement M77, which governs the application of SCR systems on ships
Yoo Byungyong, Senior Vice President of HD KSOE, said: "Hi-CLEARS safely processes ammonia leaks and treats the resulting liquid through SCR, thereby meeting both safety and environmental regulations."
Yoo Byungyong adds, "Through close cooperation with KR, we have enhanced its commercial viability, while also strengthening our global competitiveness."
Key challenges of ammonia-fuelled vessels
Ryu Hongryeul, Executive Vice President & CTO of HD HHI, stated: "This joint development marks an important achievement in addressing two key challenges of ammonia-fuelled vessels — reducing ammonia discharge and utilising it for harmful gas treatment."
Ryu Hongryeul adds, "Leveraging the strong partnership between shipyards and KR, we will further reinforce our leadership in advancing next-generation eco-friendly technologies."
Advancing international standards
Lee Yongsok, Executive Vice President of KR, stated: "This AIP goes beyond technical validation to advancing international standards. By contributing to revisions, such as IACS Unified Requirement M77, KR is helping to create the regulatory foundations that make ammonia-fuelled ships a safe and viable reality."
Lee Yongsok adds, "We remain committed to refining technical rules and requirements in line with technological progress and evolving industry needs, and to leading the decarbonisation transition as a trusted partner to the global maritime community."
