Breakthrough in LNGC propulsion

Teekay will go down in history as the first shipowner to choose low-speed, gas-injection engines to propel its LNG carriers.

In mid-December 2012 Teekay LNG Partners ordered two 173,400m3 LNG carriers at Daewoo Shipbuilding & Marine Engineering. The pair will be the first gas tankers to be powered by low-speed dual-fuel engines. MAN Diesel & Turbo will supply each vessel with two of its M-type electronically controlled gas-injection (ME-GI) engines. The Teekay order at DSME came with options for up to three sisterships.

A day before the Teekay contract the US shipping company Totem Ocean Trailer Express (TOTE) announced it was going to build two 3,100 TEU container ships that will also be powered by MAN ME-GI engines. Gas from two large LNG bunker tanks on each ship will be utilised to drive the power train. The TOTE newbuilding project also comes with options for up to three sisterships.

The TOTE and Teekay contracts herald a new era in marine propulsion. MAN has been developing this dual-fuel diesel engine design over a period of several years and the breakthrough orders in December highlight the suitability of the propulsion system for both LNG carriers and other types of ships.

MAN points out that its ME-GI design represents a logical progression in LNG carrier propulsion systems, following on from steam turbines and, more recently, the medium-speed, dual-fuel diesel-electric (DFDE) concept. The engine builder reports that the ME-GI engine is not susceptible to the methane slip that other gas-burning engines have to contend with. As such, it represents the most efficient, environment-friendly propulsion system available to the marine market.

The first commercial MAN ME-GI engine was demonstrated by licensee Hyundai before a large gathering of customers in Korea in November 2012. The engine successfully achieved 100 per cent load when powered by gas with a minimal amount of pilot oil for ignition and subsequently passed its type approval test.

MAN states that the ME-GI engine can burn either heavy fuel oil (HFO) or gas at any ratio. Although natural gas, based on the use of an LNG bunker system in ships that are not gas carriers, will be the gas fuel of choice in the majority of cases, MAN intends to introduce an LPG-burning version of its ME-GI engine in due course.

The two Teekay LNGC newbuildings at DSME are scheduled for completion in the first half of 2016. Each vessel will be powered by a pair of 5G70ME-GI engines and the gas fuel will be provided by cargo boil-off. The G-type concept is MAN’s new ultra-long-stroke engine, which has been configured to deliver an even higher overall propulsion plant efficiency. In recent years the conventional, HFO-burning G-type engine has gained the fastest market acceptance of any engine in the MAN portfolio.

The TOTE container ships will be built at the NASSCO yard in San Diego and will go into service between Florida and Puerto Rico on delivery in the fourth quarter of 2015 and the first quarter of 2016. Each vessel will be powered by an 8L70ME-GI dual-fuel, gas-powered engine. LNG