Improving Ship Energy Efficiency through a Systems Perspective

Sammanfattning: The last years have been particularly challenging for the shipping industry. Fuel prices have increased to levels only seen during the oil crisis in the 70's, and environmental regulations have grown much stricter than in the past. Climate change, at a global level, is going to become a major threat to society. Increasing energy efficiency is one of the only possibilities of reducing fuel costs and environmental impact of the shipping sector without influencing the output. However, despite the recent developments in several aspects of ship technology, little effort has been made in looking at the whole ship as an energy system. This licentiate thesis aims at filling a gap in the existing scientific knowledge on the way energy in its different forms is generated, converted, and used on board of a vessel. This is done by applying energy and exergy analysis to ship energy system analysis. The results of this analysis allow improving the understanding of energy flows on board and identifying the main inefficiencies and waste flows. As a further development of this work, these results are used as a basis for the generation and evaluation of alternatives for improving ship energy efficiency. This is applied to the three main categories of: ship operations, retrofitting, and design. Engine-propeller interaction, waste heat recovery systems and the early stages of ship design are identified as relevant aspects and their evaluation indicates that there is a relevant potential of improvement.