Turbines power up

In the quest for greater speed, ship designers are increasingly looking towards gas turbines.

Turbine driven containerships! You can almost hear the gasps of astonishment in Copenhagen and Winterthur. Containerships – the users of the worlds largest diesel engines, being driven by gas turbines – and waterjets too. This is the intention of FastShip with its 40 knot 1,432 TEU vessels which will cross the Atlantic in four days with the aid of five 50MW (68,000 bhp) gas turbines.

GE Marine and Rolls Royce are bidding for the contract. GE is offering a marinised version of its industrial 42MW (57,100 bhp) LM6000 and Rolls Royce a marinised 47.5MW (64,600 bhp) version of the industrial Trent turbine. Both are untried in the marine environment, but weighing in at around 21t, the weight saving of some 1,580t over a two-stroke engine of equivalent output makes the use of turbines a necessity. In recent tests using dry low emissions (DLE) combustors, the LM6000 turbine recorded a thermal efficiency of 42 per cent (around 200g/kWh) and produced 4.5g/kWh of NOx.

The marinised Trent will use the individual combustors as seen on the aero engines rather than the annular unit from the industrial version. Full power simple cycle efficiency is also 42 per cent and the unit has the potential to go to 50MW (68,000 bhp), says the company. While these represent the top end of the power range, there is work going on lower down the output range where turbines are beginning to build up a reasonable reputation for reliability.