GTT, CMA CGM and DNV GL have released a technical and feasibility study for a new LNG-fuelled mega box ship, the Piston Engine Room Free Efficient Containership PERFECt.
The concept vessel is powered by a combined gas and steam turbine, and is electrically driven. Exploring this novel configuration resulted in the partners identifying and analysing a propulsion concept that has the potential to offer a more efficient, more flexible and greener box ship design than current 20,000 teu two-stroke diesel engine driven ultra large container vessels.
Cossmos
In a comprehensive analysis with the DNV GL Cossmos tool, components of the potential power production and propulsion system were simulated in order to analyse the Cogas system. With Cossmos it was possible to get detailed data for the calculation of the overall fuel efficiency for a complete round voyage. Using a global FEM analysis, the project partners also evaluated the impact of the changes that were made to the general arrangement.
No Engine Room
The two 10,960 m³ LNG fuel tanks are located below the deck house, giving the vessel enough fuel capacity for an Asia/Europe round trip. With the gas and steam turbines integrated at deck level within the same deck house as the tanks, the space normally occupied by the conventional engine room can be used to increase cargo capacity significantly.
The dissociation of electric power generation from electric propulsion allows the electric power plant to be moved away from the main propulsion system, giving a great deal of flexibility. In fact, an engine room is not needed any more. The three electric main motors, which are arranged on one common shaft, can be run fully independently of each other providing increased redundancy and reliability and a high level of safety.
New Maintenance Strategies
With gas turbine-driven power production that utilises a very clean fuel as well as electric propulsion, the ship’s machinery systems will be simplified and much more robust. This approach is also expected to lead to new maintenance strategies that are already common practice in the aviation industry. Such strategies would enable shipping companies to reduce the ship’s engine crew dramatically and save costs.
Optimising the Propulsion System and Ship Design
The study also 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. The next phase of the study aims to optimise the propulsion system and ship design to attain even greater efficiency and increased cargo capacity.
Picture: General arrangement of the PERFECt ship.
