There is a growing need to run ships more efficiently and sustainably. The giant container ships used the huge two-stroke diesels, a combined gas and steam turbine and now, electric drive to the propeller.
The gas turbine merchant ships such as the Australian ro-ros, very fast trans-Atlantic container ships and the amazing Baltic express ferry Finnjet were all technically successful. But increasing cost of fuel killed off these vessels prematurely. But LNG – the “fuel of the future” combines the power and flexibility in a compact space. BIMCO and classification society DNV GL has resulted in a technical and feasibility study for a new very large containership designed around this LNG fuelled, turbine powered concept.
The design illustrates a compact and light ship producing an enormous power with the flexibility to position the combined gas and steam turbine virtually anywhere on the ship and does away with 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%.
However, the space needed for the storage of the insulated tanks is minus point. But the designers have been able to keep two 10,960Cu.m. 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.
More cargo space is ensured as large engine room is dispensed with and with the electric power generation separate from the electric propulsion, the designers have greater flexibility, of coupling three electric main motors on one common shaft. Clean fuel, simplified machinery systems with increased redundancy and a high level of safety might also be expected much like the sort of maintenance strategies in the aviation industry.
The design is still only at a concept level, but shows that there is plenty of scope for innovation in the maritime world. Meanwhile, the biggest ever two stroke diesel to be constructed is being installed in another giant container ship in Korea. Designers have more options to think about!