A taxonomy of models for investigating hydrogen energy systems

Hydrogen can serve multiple purposes within the energy system, from flexibility provider, to decarbonizing hard-to-abate sectors, to chemical feedstock. A range of model paradigms have been developed to assess the potential for hydrogen energy systems while accounting for the unique characteristics of hydrogen. This study proposes a taxonomy to classify models of hydrogen energy systems. The taxonomy is based on a review of 29 studies that proposed a taxonomy for energy models in general. This review identified 124 categories that are commonly used to map models, which were grouped into six major categories. This general taxonomy was then adapted to hydrogen, leaving only 32 categories in four major categories. Nine hydrogen archetypes that cover the entire spectrum of studies of hydrogen energy systems were identified. Each of these archetypes was mapped against the categories defined which allowed identifying common gaps across archetypes and degree of interrelationship between them. The environmental and high spatial resolution aspects are only covered by one archetype. The correlation between archetypes assessed in this study can be used to identify opportunities for soft-linking. All the archetypes provide partial answers and using a modeling suite composed of various models could address shortcomings of individual archetypes. All models have a strong focus on technology and costs, with other aspects such as the innovation cycle, market design and policy levers to promote deployment receiving little focus. Capturing these dynamics in the hydrogen archetypes would enable a more holistic analysis and would also facilitate subsequent action.