MAN: Even Bigger Propellers and Lower Speed Engines Should Give 4-7% Bunker Savings

MAN Diesel & Turbo says the engine is the "world's first" IMO-certified two-stroke engine with Tier III NOx Control and Exhaust Gas Recirculation Systems (EGRS).

MAN Diesel & Turbo SE (MAN) Monday said it estimates that design updates to tankers and bulk carriers to accommodate even larger propellers, in conjunction with even lower speed engines, should give bunker savings of some 4-7 percent along with a similar reduction in CO2 emissions.

The comments came alongside an announcement by MAN that it had delivered such a low speed engine - part of its G-series - that it says is the "world's first" IMO-certified two-stroke engine with Tier III NOx Control and Exhaust Gas Recirculation Systems (EGRS).

Two of the engines are to be installed on two 158,000 m3 capacity Suezmax tankers owned by Ditas Shipping.

MAN notes that, while there are already IMO Tier III-compliant vessels with EGR systems in service, these two newbuilding vessels will be the first to have been officially certified as complying with Tier III emission restrictions within North American and United States Caribbean Sea NOx Emission Control Areas (NECAs), having had their keel laying after the January 1, 2016 deadline.

"EGR is a NOx emissions-control technology that works by recirculating a portion of an engine's exhaust gas back to the engine cylinders," says MAN.

The company adds that an automated control system allows the ship's crew easy operation, as well as accurate and quick reactions to engine load variations.

"Following efficiency optimisation trends in the market, MAN Diesel & Turbo thoroughly evaluated the possibility of using even larger propellers and thereby engines with even lower speeds for the propulsion of tankers and bulk carriers," explained the company, adding that "such vessels may be more compatible with propellers with larger diameters than designs so far used."

As such, MAN says that vessels may able to glean higher efficiencies if the aft-hull design is adapted to accommodate a larger propeller.

In October, Alfa Laval said its new pressurized economizer, combined with exhaust gas recirculation technology, which was developed with MAN, demonstrated the potential for "massive fuel savings" and could turn NOx limit compliance into profit.