Korean Register grants AiP for ammonia-fueled ship safety solution Hi-CLEARS

Korean Register (KR) has granted Approval in Principle (AiP) for the ammonia-fueled ship safety solution known as Hi-CLEARS, developed in collaboration with HD Hyundai Heavy Industries (HD HHI) and HD Korea Shipbuilding & Offshore Engineering (HD KSOE). The announcement was made on September 11 at Gastech 2025 in Milan, Italy.

Hi-CLEARS, short for Hyundai integrated Clean Liquid based Ammonia Release mitigation system with SCR, is designed to capture ammonia gas that may leak during vessel operation. The system converts the gas into aqueous ammonia and repurposes it as a reductant in a Selective Catalytic Reduction (SCR) system. This process prevents ammonia discharge into the atmosphere and sea while supporting regulatory compliance.

The approval follows a joint development project aimed at resolving safety and regulatory challenges surrounding ammonia-fueled vessels. The project also supports efforts to establish international technical standards for future applications.

KR has played a role in revising IACS Unified Requirement M77, which governs the use of SCR systems on ships. The revised standard now allows aqueous ammonia and ammonia to be used as reductants, creating a technical framework for the commercialization of Hi-CLEARS.

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. Through close cooperation with KR, we have enhanced its commercial viability while also strengthening our global competitiveness.”

RYU Hongryeul, Executive Vice President & CTO of HD HHI, added:
“This joint development marks an important achievement in addressing two key challenges of ammonia-fueled vessels—reducing ammonia discharge and utilizing it for harmful gas treatment. Leveraging the strong partnership between shipyards and KR, we will further reinforce our leadership in advancing next-generation eco-friendly technologies.”

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-fueled ships a safe and viable reality. We remain committed to refining technical rules and requirements in line with technological progress and evolving industry needs, and to leading the decarbonization transition as a trusted partner to the global maritime community.”