The potential of hydrogen to fuel international shipping

Today the way energy is produced and consumed is under debate as it is increasing the atmospheric concentrations of greenhouse gases (GHG), which can cause dangerous anthropogenic interference with the climate system. This means that a de-carbonisation of the global energy system is required. Shipping represents the biggest global low cost international freight transport service, and today it accounts for about 3% of the world's total GHG emissions. Such a percentage is projected to increase by 50% to 250% in the period to 2050. The projected shipping emissions trajectory, therefore, does not seem compatible with the de-carbonisation of the global energy system necessary to meet the internationally agreed goal of reducing the emissions in all sectors and ensure that the temperature rises in 2100 will not be greater than 2_C degree. Since shipping energy demand is mainly satisfied by fuel oil, recent new regulations on efficiency and air pollution have been introduced (EEDI, SEEMP), and instruments that would cut GHG emissions from shipping are under discussion. In the short term (5-10 years) the industry is aiming to reduce its emissions through a combination of technological and operational developments, however in the long term a switch to an alternative fuel may be required. Among the options, hydrogen with fuel cell systems (FCs) is seen by many as one of the long term solutions. Its attraction is not only for its zero operational emissions but also for the higher efficiency that could be achieved on board. Hydrogen and FCs are also seen as promising technologies that can support climate change and energy security goals in several sectors of the energy system. The most attractive uses of hydrogen within the context of a de-carbonization of the energy system are: for storing renewable energy, for heating, and as fuel for the transport sector. Moreover, it can increase the operational flexibility as it can connect different energy sectors and energy transmission and distribution networks. The energy and the shipping systems are interrelated, so if the de-carbonisation of the global energy system could be achieved with the use of alternative energy and fuels including hydrogen, the same could be experienced in shipping with a widespread switch to the adoption of hydrogen as alternative fuel within the coming decades. The purpose of this thesis was to learn more about the potential for hydrogen as a future fuel in shipping. The focus is on a computational modelling approach that is considered to lead to new useful contributions. This study proposes a framework based on a soft-linking technique to examine the potential of using hydrogen in shipping. The framework connects together a global integrated assessment model (TIAM-UCL) and a shipping model (GloTraM). GloTraM is a bottom-up shipping simulation model that is used to evaluate pathways towards a low carbon shipping system; TIAM-UCL is a bottom-up energy system model that is used to investigate possible pathways to reduce the energy and carbon density of the global energy system. The first objective of this study is the development of a new modelling approach that soft-links two existing models in order to improve the modelling representation of hydrogen take up in shipping. The hypothesis is that the model linkage is more representative for exploring specified scenarios, forecasting investment decisions for hydrogen powered ships in conjunction with the hydrogen infrastructure development than the two separate models. The second objective is the analysis of the possible use of hydrogen under specific scenarios in order to understand at a global level the implications of providing and using hydrogen in shipping. The hypothesis is that the model linkage is able to explore the broader circumstance in which it would be possible to see an uptake of hydrogen in shipping and what it might mean for the contribution of shipping in avoiding 2_C of warming. Based on this objectives, this research aims to answer the following research questions: Can an integrated framework that combines two different models improves the modelling representation of hydrogen uptake in shipping compared to the current representations found in the literature? What type of results does the integrated framework provide regarding the potential of hydrogen to compete with LNG and current marine fuels to fuel international shipping? Under what circumstance would hydrogen be able to compete with LNG and current marine fuels in shipping and what would be the main economic and environmental implications? The comparison between the results of the independent and the integrated framework simulations of a specific set of scenarios has highlighted the capability of the framework of modelling the investment decision for ships powered by hydrogen in conjunction with the development of a hydrogen supply infrastructure with a more robust approach compared with the energy and shipping models. Evidence of the modelling improvement was found in: the ability of the model to simulate the equilibrium between marine fuel prices and demands, the ability of the model to capture the dynamics between the carbon price and the shipping fuel mix (how these outputs influence each other), the ability to generate fuel price projections that overcome the limitation of the linear property of the energy system model, the ability of capturing the dynamics between the transport demand among regions and the fuel mix evolution of the global feet. Moreover, a number of circumstances for the potential uptake of hydrogen over LNG were found in this thesis; the key circumstances are: the introduction of an emissions cap in shipping, a competitive hydrogen price and investment costs of hydrogen technologies on board ships (fuel cells and hydrogen storage technologies), and finally the supply of hydrogen mainly based on natural gas and biomass with CCS technology or electrolysis in case of an absence of CCS. The main implication of a switch to hydrogen is that shipping emissions would be reduced significantly over time. This topic was identified as being of importance to assist ship owners and fuel providers in understanding the potential of use of hydrogen in shipping, and to assist policy makers in the development of effective GHG policy for shipping and in understanding the implications of using hydrogen in shipping within the context of a de-carbonised energy system. It is hoped that information from this study may be useful in creating awareness of the potential that hydrogen might have in shipping and in creating incentives for further research required for exploring this option from different perspective. Moreover, this study explores the application of a relative new modelling technique of soft-linking two existing models. The experience engaged in developing such a link could be useful to educators and modellers interested in the soft-linking modelling approach.