MAN Energy Solutions has acknowledged the growing role of hybridisation in deepsea shipping by establishing a default set-up for using power take-off with its dual-fuelled two-stroke engines.
The company used the configuration to show how an 11,000 teu, gas-fuelled container ship can be made more efficient by harnessing power take-off (PTO) to generate electricity from its main engine. MAN cited a recent application as the inspiration for a study which found that connecting a PTO to an ME-GI engine could cut fuel consumption by 6.4%, or 165 tonnes of gas fuel per 18,000 nm trip. That equates to 1,238 tonnes less fuel a year.
“The new fuels, regulations and the challenging environment in the marine business over the past years have created a complicated equation in terms of optimising a future vessel,” said the authors of the study. “In order to address the increasing needs from vessel operators, MAN has gathered data and operating experience and created a default set-up.”
MAN’s solution is to connect a 2.4MW power take-off to an eight-cylinder G95ME-GI engine (with a maximum continuous rating of 42.31MW at 76.9 rpm). The company argues that the inherently better efficiency of two-stroke engines means that using the main engine to generate electricity while sailing is more efficient than using the auxiliaries.
To optimise fuel efficiency, the company deploys the latest version of both its ultra-long stroke G95 engine and the ‘Mark 2’ update of its ME-GI gas injection concept. It also includes the recently developed pump vaporiser unit. This combines the cryogenic pumps and vaporiser in one unit, simplifying the fuel gas supply system.
The efficiency gain can be used to either improve sea endurance, allowing for longer time between bunkering, or to reduce the size of LNG tanks needed manage the same voyage. In the case used, the tank could be shrunk by 350m3 to 5,950m2. This would also slow the boil-off rate, meaning smaller gas-handling equipment can be installed. Other benefits would include shorter bunkering times, while storing less fuel on board also simplifies operations.