HD Korea Shipbuilding & Offshore Engineering (KSOE) and HD Hyundai Heavy Industries (HHI) received an approval in principle (AIP) from ABS for an ammonia reductant supply system for selective catalytic reduction (SCR) in ammonia-fuelled ships. 

The AIP was presented at Gastech 2023 in Singapore, in a ceremony attended by representatives from both companies and the Liberian International Ship & Corporate Registry (LISCR).

The system utilises the ammonia carried on board as the SCR reductant to remove NOx from emissions as opposed to the urea used in traditional diesel propulsion.

The Motorship notes that using ammonia rather than urea in the catalytic reaction in the SCR results in the conversion of NH3 and NOX to diatomic nitrogen (N2) and water (H2O). This minimises emissions of unburned NH3 (ammonia slip) and the potential formation of nitrous oxide (N2O), a more potent GHG gas.