A dual-fuel generator engine employing hydrogen gas as fuel has been approved in principle (AiP) by ClassNK for a 160,000 cubic meter (cbm) liquid hydrogen carrier created by Kawasaki Heavy Industries (KHI).

The dual-fuel generator engine, according to KHI, has the flexibility to switch between hydrogen and low-sulfur fuel oil (LSFO). When hydrogen fuel is chosen, boil-off gas naturally evaporating from the ship’s liquefied hydrogen cargo tanks is used as the main fuel to generate and supply electricity on board at a calorie-based mixed ratio of 95% or higher, which is expected to significantly reduce greenhouse gas emissions from the ship.

The classification group noted in a statement that this was its first AiP for a dual-fuel generator engine using hydrogen gas as fuel.

The integrated design of the KHI liquid hydrogen carrier as well as its cargo containment system (CCS), cargo handling system (CHS), and dual fuel main boilers that utilize hydrogen boil-off gas as fuel have all received AiPs from ClassNK.

On the basis of its Part N of Rules for the Survey and Construction of Steel Ships incorporating the IGC Code and its Guidelines for Liquefied Hydrogen Carriers incorporating the IMO’s interim recommendations for Carriage of Liquefied Hydrogen in Bulk, ClassNK performed the design review of the dual fuel generator engines using hydrogen gas as fuel and related machinery systems and arrangements in the most recent examination.

The AiP was issued after a thorough safety evaluation was carried out based on the findings of the HAZID risk assessment.