The remaining chapters are organised as following: chapter 2 comprises of a literature review of the main studies concerning the use of hydrogen as a fuel in shipping. The purpose of this chapter is the identification of the gaps in the literature that leads to
Chapter 1. Introduction 18
the research questions. Existing approaches are evaluated and a particular focus is on the computational modelling methods.
In chapter3the modelling representation of hydrogen uptake in shipping is examined in order to identify the specifications required for a complete and adequate representa- tion. The bottom-up energy model TIAM-UCL and the bottom-up shipping model GloTraM are analysed in this chapter with their relative representational capacity of the target system. The studies that have linked two different models are also reviewed. Finally the gaps in the literature are identified as well as the research questions.
Chapter4identifies an appropriate method that can be used to answer the identified research questions, and then develops the method used to soft-link two existing mod- els (TIAM-UCL and GloTraM). Linking two computational models is a relatively new method, therefore this chapter starts by critically analyses existing studies that have ap- plied soft-linking methods. A number of steps are identified in order to soft-link the two models. Each step is developed in greater detail along with the associated assumptions. Chapter 5 explores the evidence as to whether the soft-linking framework improves the modelling representation of hydrogen uptake in shipping. This chapter is intended to address the first research question by describing and comparing the results of inde- pendent simulations of TIAM-UCL and GloTraM and the results of TIAM-GloTraM. Two different scenarios are examined. They explore the evolution of the global energy system in conjunction with the shipping system under two different emissions reduction targets.
Chapter 6 examines the potential of hydrogen to be an alternative marine fuel. This chapter is intended to address the second research question. A different scenario is explored with diverse circumstances to explore what may lead to the adoption of hydrogen as a fuel in shipping. The results from this scenario are described in detail, analysing the implications in both the energy and the shipping systems. This chapter comprises also of a robustness analysis where the resulting inferences are tested by exploring a number of scenarios. This analysis is carried out in order to understand the relationship between given uncertain input factors and the model output. The robustness analysis highlights the relationship between specific input factors and the possible uptake of hydrogen in shipping. It also identifies specific dynamics between the energy and the shipping systems that can influence the potential of hydrogen to be an alternative marine fuel.
Chapter 2
Literature review
2.1
Introduction to the literature review
This chapter provides a literature review of the main studies concerning the use of hy- drogen as a fuel in shipping. The aim is to identify possible gaps in the literature and therefore the needs for further investigations. The idea of hydrogen in shipping is asso- ciated with the portfolio of technology solutions that the shipping industry has in order to improve its energy efficiency, and to reduce its carbon intensity. Different scopes have been investigated for such technology solutions in shipping. The efficiency of hydrogen powered ships, for example, is under investigation with the analysis of operating pro- totypes. The potential efficiency of hydrogen in combination with fuel cell systems on board ships has also been investigated by studies that have focused on maritime appli- cations of fuel cell systems. Other scopes have included environmental and economic factors to drive the possible adoption of hydrogen in shipping, taking into account the supply of hydrogen. A number of approaches have been used such as the analysis of empirical data, the cost-benefit analysis, cross-modal comparison, life cycle assessment, general assessment, simulations of a ship’s main engine, and the use of computational models to simulate the shipping system or the energy system. In this thesis particular focus will be given to the studies that have used a computational modelling approach, although it is recognised that other approaches have already provided a number of useful insights.
The modelling approach has been applied with different purposes; for example, some studies have discussed on the potential of hydrogen in shipping but with the broader scope of studying alternative fuels in shipping. Other studies have focused on hydrogen as fuel but without considering shipping among the possible users. The implications for the modelling representation of the use of hydrogen in shipping will be reviewed in this chapter. The purpose of such a review is the identification of the required specifications that need to be considered for hydrogen’s modelling representation in shipping.
This chapter is organised as follows: section 2.2 provides a review of existing ap- proaches evaluating methods used and conclusions. In section2.3the existing approaches are evaluated for being the most suitable method to investigate the potential use of hy- drogen in shipping. Section 2.4 provides a review of other relevant studies to analyse the background theory and identify implications on the modelling representation of the use of hydrogen in shipping. Finally, the identified implications are discussed in section
Chapter 2. Literature review 22
2.5, which also provides an examination of how hydrogen has been modelled and how such representations fit with the identified implications.