MAN Energy Solutions has developed a new small-bore engine solution that complies with China’s Stage II – commonly known as the C2-emission standard (GB15097 regulation) – due to enter into force in July 2021. The new legislation will primarily apply to inland waterways, coastal areas and most rivers, covering  domestic bulk carriers, feeder containers, oil tankers, passenger RoRos and government vessels. The company expects the introduction of C2 to grow sales of its small-bore, four-stroke MAN L21/31 engine type as a result.

Directive limits relate not just to NO_x and hydrocarbons (HC) but also to particulate matter (PM), which is attracting increased focus from the maritime industry. The limits are particularly challenging for type 2 marine engines with single-cylinder displacements of under 15 litres, and an overall power output of <2,000 kW.

Finn Fjeldhøj, Head of Small-Bore, Four-Stroke Engineering, MAN Energy Solutions, said: “As soon as C2 came on the horizon, we realised it was an excellent opportunity for our MAN L21/31 engine, whose compactness, low fuel-oil consumption and power rating make it particularly suited to this segment. Extensive testing shows that it complies with C2 particulate-matter limits without needing a particulate filter, while an SCR system will be required to meet NO_x requirements. In practice, such an SCR system will be sparingly employed to optimise engine efficiency and limit after-treatment operational expenses. We are confident that this practical solution will win favour in vessels sailing Chinese inland-waterways.”

MAN Energy Solutions states that the L21/31 can fulfill classification requirements as both controllable-pitch-propeller (CPP) propulsion and genset applications.  Based on recent research, MAN is already capable of pursuing the engine’s official emission certificates from the China Classification Society but continues to develop more advanced solutions with its licensees to further reduce the environmental impact of the engine, as well as customers’ operational costs.