A JOINT technical and feasibility study carried out by France-based marine engineering company, Gaztransport et Technigaz (GTT), shipping line CMA CGM and international certification body DNV GL have released their findings for a new 20,000 TEU container ship that doesn't have an engine room.
The vessel is LNG-fuelled, powered by a combined gas (COGAS) and steam turbine and is electrically driven, The Maritime Executive reported.
With the gas and steam turbines integrated at deck level within the same deck house as the LNG tanks, the space normally occupied by a conventional engine room can be used to increase cargo capacity by approximately 300 container slots compared to a heavy fuel oil-fuelled ship.
The Piston Engine Room Free Efficient Containership (PERFECt) concept vessel thereby generates greater revenues and reduces the payback time for the additional CAPEX required, says DNV GL. The design is claimed to have the potential for better efficiency and flexibility than current 20,000 TEU two-stroke diesel engines driven ultra large container ships.
Business director for LNG-fuelled ships at DNV GL - Maritime, Gerd Würsig says a modern, land-based combined cycle LNG-fuelled power plant will reach fuel-to-power efficiency ratios of up to 60 per cent, which is higher than conventional diesel engines, which can achieve up to 52 per cent. In addition, the power density by volume and weight is much higher for a COGAS system.
The study suggests that optimising the power plant through minimising the steam turbine size, reducing power capacities, condenser cooling and using a two-stage pressure steam turbine and steam generator will increase the system's efficiency further.
"Gas turbines associated with steam turbines in co-generation mode are ideal for the efficient utilization of LNG as a fuel," says LNG bunkering programme director at GTT, Arthur Barret.
"This new design combines the exceptional volumetric efficiency of membrane containment technology with flexible electric propulsion to save even more cargo space compared to a conventional design."
The next phase of the design process aims to optimize the propulsion system and ship design to attain even greater efficiency and increased cargo capacity.
Source : HKSG.