Modelling, analysis and optimisation of ship energy systems
Doctoral thesis, 2016

Shipping is the backbone of today's economy, as 90% of global trade volumes is transported by sea. Much of our lifestyle today is only made possible by the existence of shipping as a cheap and reliable mean of transportation across the globe. However, the shipping industry has been challenged in the latest years by, among others, fluctuating fuel prices and stricter environmental regulations. Its contribution to global warming, although today relatively small, has been set under scrutiny: for shipping to be part of a sustainable economy, it will need to reduce its emissions of greenhouse gases. Increasing ship energy efficiency allows reducing fuel consumption and, hence, carbon dioxide emissions. The latest years have witnessed a multiplication of the efforts in research and development for increasing ship energy efficiency, ranging from improvements of existing components to the development of new solutions. This has also contributed to ship energy systems to become more complex. The optimisation of the design and operation of complex systems is a challenging process and the risks for sub-optimisation are high. This thesis aims at contributing to the broader field of energy efficiency in shipping by adopting a systems perspective, which puts a special focus on system requirements and on interactions within the system. In this thesis, the energy systems of two case study ships were analysed using energy and exergy analysis to identify energy flows and inefficiencies. Then, solutions for improving the energy efficiency of the existing systems were proposed and evaluated accounting for the ship's observed operating range and for how added elements influenced the existing systems and their performance. The results of this thesis show the importance of modelling the interactions between different parts of the energy systems. This allows not only a more accurate estimation of the benefits from the installation of new technologies, but also the identification of potential for additional energy savings. This is particularly important when the broad range of ship operations is included in the analysis, rather than focusing on the performance of the system in design conditions. In addition, the results of this thesis also show that there is potential for further improving ship energy efficiency by putting additional focus on heat losses from the engines and on how to efficiently recover them.

Hörsal Beta, Hus Saga, Campus Lindholmen
Opponent: Alan Murphy


Francesco Baldi

Chalmers, Shipping and Marine Technology, Maritime Environmental Sciences

Energy and exergy analysis of a cruise ship

Proceedings of ECOS 2015 - The 28th international conference on efficiency, cost, optimisation, simulation and environmental impact of energy systems,; (2015)

Paper in proceeding

Energy and exergy analysis of ship energy systems - The case study of a chemical tanker

International Journal of Applied Thermodynamics,; Vol. 18(2015)p. 82-93

Journal article

Life as we know it today depends on the great achievements in ship technology of the latest century. If today we can all afford to buy smartphones and exotic fruits it all depends on the availability of a cheap and reliable way of transporting goods across the world: shipping. Unfortunately, expected future trends do not look promising. Shipping is expected to increase its emission by between 50% and 250% compared to 2012 levels by 2050. These same emissions over the same period should be reduced by 80% if shipping is expected to contribute to the reduction of CO2 emissions required to keep global warming at bay. Research in ship energy efficiency is therefore necessary. In this thesis I approached this subject by taking a step back and trying to look at the whole system. Others have worked on optimising the efficiency of the propeller or of the engines, achieving astonishing results, but few have asked themselves the question of how to make that same propeller and that same engine to work best together. In this thesis I employ a systems approach, looking at system interactions and at how the system is operated more than at individual components. I show that in this way it is possible to better estimate how much fuel can be saved when improving the system by, for instance, installing a waste heat recovery system. I also show that when optimising the energy system of a ship, the savings can be higher if one looks at the whole system instead of at its individual parts.

Driving Forces

Sustainable development

Areas of Advance



Subject Categories

Energy Engineering



Report. X - Department of Shipping and Marine Technology, Chalmers University of Technology, Göteborg, Sweden

Hörsal Beta, Hus Saga, Campus Lindholmen

Opponent: Alan Murphy

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