Korean Register (KR) has reported the results of land-based tests of an exhaust gas after-treatment system developed for megawatt-scale ammonia-fuelled engines.
The system was developed by KR in collaboration with EcoPro HN and HD Korea Shipbuilding & Offshore Engineering (HDKSOE). Testing confirmed a 95% reduction in nitrogen oxides (NOx) emissions and a 99.7% reduction in ammonia (NH₃) emissions. Ammonia slip was reduced from an initial level of 10,000 parts per million to around 30 parts per million.
The prototype underwent extended operational testing at the KR Green Ship Test & Certification Center, where its durability and emissions performance were verified.
The development forms part of the government-funded project ‘Comprehensive Management Technology Development for Ship Greenhouse Gas Emissions’, supported by South Korea’s Ministry of Oceans and Fisheries and the Korea Institute of Marine Science & Technology Promotion.
According to KR, the system is South Korea’s first microwave catalyst-heating exhaust gas after-treatment system applied to megawatt-scale ammonia-engine exhaust.
Ammonia combustion does not produce carbon dioxide or sulphur oxides, but exhaust gas from ammonia engines can contain nitrogen oxides, nitrous oxide and unburned ammonia. Nitrous oxide is a greenhouse gas with a global warming potential estimated at 273 to 298 times that of carbon dioxide over a 100-year period.
The after-treatment system is designed to address a technical challenge associated with catalytic emissions control. Catalysts must operate within a specific temperature range to convert pollutants into less harmful substances. The system uses a microwave-based catalyst heating method which, according to KR, enables rapid catalyst activation and supports stable emissions reduction across different engine operating conditions.
Kim Daeheon, Executive Vice President of KR, said: ‘For the commercialisation of ammonia-fuelled vessels, securing exhaust gas after-treatment technology is just as important as fuel technology itself. Through this demonstration, we have validated the effectiveness of the jointly developed system. Going forward, we plan to expand its application to various dual-fuel engines and actively support the transition toward carbon-free shipping.’
Several ammonia dual-fuel vessels are scheduled to enter service from 2026 as shipowners begin testing ammonia propulsion in commercial operations. Separately, KR has launched a working group focused on developing global safety management and marine discharge standards for ammonia effluent generated by ammonia-fuelled ships.
