Existing studies regarding hydrogen in shipping have been examined focusing on the techno-economic modelling methods. Other relevant models have been discussed high- lighting factors and implications for the representation of alternative fuels in shipping and hydrogen in models. The target system in this thesis is the hydrogen uptake in
Chapter 2. Literature review 32
shipping. According to Weisberg (2012), before accounting for the representational ca- pacity of a model it is important to establish the relationship between the target system and the model. Such a relationship can be analysed looking at the background theory of the existing studies examined above. If we assume that this background theory is rich enough, then we are able to highlight the feature set that is needed in a model to be representative of our target system.
Hydrogen on board ships implies the representation within a model of the technolog- ical concept design of hydrogen and the associated main propulsion system in a certain level of detail. For example, if hydrogen was to be used with fuel cells, all implications associated with the technological components should be represented, such as efficiency of fuel cells, power density, required safety systems, effect on the cargo capacity and range, capital and operational costs.
A hydrogen powered ship would operate within the shipping system, and it would compete with other alternative and conventional ships in different shipping markets characterised by specific voyage, operational specifications, ship type and size. Moreover, other factors can influence the viability of a hydrogen powered ship such as the shipping regulatory framework and changes in the transport demand. This implies also that the representation of the shipping system within a model should be included in a certain level of detail.
Hydrogen needs to be available at port refuelling terminals, therefore the represen- tation within a model of the hydrogen supply chain for shipping should be included. Hydrogen production, transportation and storage should be modelled in a certain level of resolution. Hydrogen supply chain would interact with the rest of the global energy system, competing for primary energy resources, and satisfying the demand of other sectors. This implies also that the representation of the energy system within a model should be included in a certain level of detail.
Finally, the price of producing hydrogen would affect the demand for such fuel and at the same time the demand would affect the hydrogen price. A need to capture the balance of supply and demand is required in a model such as in the approach used in
EPA (2008a).
Table 2.1 summarises the feature set of an ideal model that we assume to be rep- resentative of the hydrogen uptake in shipping. These specifications define the feature set of an ideal model that is assumed to be representative of the hydrogen uptake in
shipping.
Table 2.1: Specifications for the representation of hydrogen as a fuel in shipping and required model feature
Specifications Required model’s feature Technological details of the con-
cept design options for hydrogen and main machinery systems on board ships
Accounting for the key technological components, their energy and emissions factors
Technical compatibility of hydrogen technologies and other energy efficiency technologies
Impact of weight and volume of hydrogen storage systems on board
Accounting for the costs of hydrogen storage sys- tems, costs of the associated main machinery and costs of maintenance of hydrogen-main machinery option, and other associated costs
Economic analysis of hydrogen- main machinery option
Simulation of the investment evaluation process of hydrogen technologies along with all the other al- ternative options
Details of the shipping system specifications
Segmentation by ship type and size
Characterisation of voyages, operational data and routes
Accounting for current and main alternative fuels competitor
Accounting for current and future environmental and energy efficiency shipping regulations
Technological details of the hy- drogen supply chains for port ter- minals
Accounting of different hydrogen infrastructure pathways
Costs of producing, transporting and storing hy- drogen
Accounting for the emission effects of bringing hy- drogen to port terminals
Details of the energy system specifications
Interaction of hydrogen supply chains for shipping with the rest of the global energy system
Accounting of competition for primary energy re- sources
Accounting of spatial factors
Influence of the changes in transport demand of en- ergy commodities
Accounting of regulations on global CO2 emissions
reduction targets
Hydrogen price for shipping Balance of supply and demand for hydrogen in ship- ping
In general, hydrogen modelling representation can be found in the literature in two different types of models: in energy models in which the focus is on the representation of the hydrogen supply chain, and in sectoral models in which the focus is on the rep- resentation of hydrogen end-user technologies. Such models differ from each other in
Chapter 2. Literature review 34
their aims, system boundary and geographical scale, and in theory they are all suitable to represent hydrogen in shipping but in a different manner.
Some of these models focus on the hydrogen supply infrastructure at a local or national scale, answering questions regarding the best configuration that optimises a specific object function. In these studies a greater level of technological detail on the hydrogen supply chain is provided, however many inputs such as energy resource avail- ability and demand are exogenous to the models. These types of models are suitable for assessing the deployment of hydrogen supply chain technologies on a local scale, for the assessment of the refuelling process of hydrogen in a particular area, for example. Due to the international nature of the shipping industry, an aggregation at global level of resolution is considered more appropriate. Moreover, these models generally lack the ap- propriate technological details of hydrogen end-user technologies, for example hydrogen powered ships are rarely included. Moreover, they lack an economic analysis to assess the market penetration of hydrogen end-user technologies, and the interactions with the rest of the energy system are not modelled.
In contrast, other models have a complete representation of the energy system, in which the hydrogen supply chains and hydrogen end-user technologies are both modelled. The level of resolution of such models depends on the system boundary (e.g. only one sector, the whole energy system), and on the geographical scale (e.g. local, regional, global). Such models have a common aim, which is the simulation of consistent scenarios of change in the energy system under specific emissions reduction constraints (Schafer,
2012). The impacts of hydrogen technologies on the energy system can be assessed through the analysis of such scenarios. On one hand these types of models have a good representation of the energy system and an appropriate level of technological detail on the hydrogen supply chain. On the other hand they have a poor level of technological detail of hydrogen end-user technologies and energy service demand. An example of this type of model is described in Taljegard et. al. (2014), where a bottom-up energy model was used, and in which the entire shipping fleet was divided into only three categories: container, coast and ocean–going ships.
In contrast to the energy model discussed above, hydrogen can be represented also in models that aim to represent a specific sector. Generally, in these types of mod- els the focus is on the hydrogen end-user technologies rather than on the supply chain technologies. These models can have a good level of technological detail of hydrogen
end-user technologies, and are often used to analyse the market penetration with specific economic evaluations. The literature is rich of models for hydrogen in the road trans- portation system, and few examples can be found for hydrogen in shipping. These types of models generally lack a proper level of technological detail of the hydrogen supply chain and the energy system.
In conclusion, based on the identified specifications there is no existing model that can be considered representative of the hydrogen uptake in shipping. Energy models include some factors and shipping models include other factors. Rarely are they used in conjunction to explore the balance of supply and demand. The bottom-up energy system model TIAM-UCL and the bottom-up simulation model of the shipping system GloTraM are examples of these types of models. A close look at these specific models can help to identify how the representation of the target system may be improved.
Chapter 3
Methodology and research
question refinement
3.1
Introduction to the methodology
The conclusion from the previous chapter is that an existing model that can be con- sidered being fully representative of the hydrogen’s uptake in shipping does not exist. Energy system models and shipping models can partially be considered representative as they do not include all specified specifications. In this chapter, a possible framework for a complete representation of our target system is examined. The framework is composed of the bottom-up energy system model TIAM-UCL and the bottom-up shipping system model GloTraM. The representation of hydrogen in both models is assessed against the required specifications with the purpose of identifying shortcomings and areas of im- provement. Hybrid models that link together two different models are also examined in order to evaluate if they are an appropriate method to resolve the gap identified in the literature. This analysis will motivate the two the research questions.
This chapter is organised as follows: the theoretical representational capacity of the shipping model TIAM-UCL is assessed in section 3.2, while section3.3 assess the theo- retical representational capacity of the energy system model GloTraM. Finally, section
3.4 justifies why a linking approach can be an appropriate method for the study of hy- drogen as a fuel in international shipping, and identifies the gap in the literature and the research questions.