A review on the use of gas and steam turbine combined cycles as prime movers for large ships. Part III: Fuels and emissions

Abstract

The aim of the present paper is to review the prospects of using combined cycles as prime movers for large ships, like, container ships, tankers and bulk carriers. The paper is divided into three parts of which this paper constitutes Part III. In Part I, the environmental and human health concerns of international shipping were outlined. The regulatory framework relevant for shipping and the design of combined cycles were discussed. In Part II, previous work and experience were reviewed, and an overview of the implications of introducing combined cycles as prime movers was included. Here, marine fuels are discussed, and the pollutant emissions of gas turbines are compared with those of two-stroke, slow-speed diesel engines. Burning liquid fuels of lower quality than distillate fuels in gas turbines is feasible, provided the fuel is pre-treated, fuel additives are added and hot sections of the gas turbine are washed regularly. However, the efficiency of the gas turbine decreases. Partly because of using different fuels, and partly because of different combustion processes, the quantities of pollutant emissions from gas turbines are substantially lower than those of diesel engines.