According to ship owners society, Bimco, an interesting collaboration between cryogenic engineers GTT, containership giant CMA CGM and classification society DNV GL has resulted in a technical and feasibility study for a new very-large containership designed around an LNG-fuelled, turbine powered concept.
This combined gas and steam turbine, such as those found aboard warships, for instance, but with electric drive to the propeller, makes for an interesting concept.
This design illustrates a number of advantages that emerge from such a propulsion arrangement. Compact and light, while producing enormous power, the combined gas and steam turbine can be positioned virtually anywhere on the ship and does away with the need for a large engine room stuffed with machinery. The electrical propulsion motors can be positioned near to the propeller shaft they drive. And while the fuel-to-power efficiency ratios of conventional diesel engines can be up to 52%, a modern land-based combined cycle LNG fuelled power plant will reach efficiencies of 60%.
The downside of LNG as marine fuel has always been seen as the space needed for the storage of the insulated tanks. But the designers have been able to situate two 10 960 cubic metre LNG fuel tanks, with the combined gas and steam turbine installation above them, under the bridge superstructure. These two tanks would provide sufficient range for the ship to make an Asia/Europe round trip between bunkering.
With no engine room to eat into the below-decks cargo space, there would be more room for cargo. And with the electric power generation separate from the electric propulsion, the designers have been given even greater flexibility, the design suggesting three electric main motors can be arranged on one common shaft. Clean fuel, simplified machinery systems with increased redundancy and a high level of safety might also be expected, say the designers, leading to the sort of maintenance strategies that are common practice in the aviation industry.
