The rapid growth in the LNG shipping market has been long predicted, challenging many of the previously accepted industry precepts. Larger vessels with alternative propulsion systems have been investigated, designed and ordered. Outside of the marine shipping sector, the gas turbine has become firmly established as the prime mover of choice for the oil and gas industry, powering facilities and pipelines. The use of compact, lightweight and reliable gas turbine power can demonstrate significant economic and technical advantages in LNG carriers.

Traditionally, LNG carriers have been powered by a steam boiler, fuelled by a combination of boil-off gas and heavy fuel oil (HFO). Steam propulsion systems are heavy and expensive to install, consume valuable cargo space and require sea-going engineers with steam qualifications which are becoming increasingly scarce.

In close consultation with large oil companies, noted industry experts and key shipyards, Rolls-Royce has developed a number of alternative LNG carrier propulsion systems that deliver increased cargo carrying capacity, enhanced operational flexibility and demonstrable through life cost savings. These are modern and highly efficient integrated systems that provide a reduction in operating costs when compared with existing steam and other proposed alternatives.

The result is a range of environmentally friendly power and propulsion systems based on the state of the art MT30 gas turbine that fully meet the requirements of large (145,000m3 > 250,000m3) LNG carriers.

This paper describes the systems, installation benefits and operational advantages, including solutions for all applicable auxiliary and supporting systems. The results of a comprehensive economic model of all competing propulsion systems are presented and analysed, further demonstrating the financial benefits and advantages.

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