Evaluating thermal energy use in hydrogen production and import

In order to reach climate goals and limit global warming, an energy transition has to be made away from fossil fuels and towards renewables. Hydrogen has been recognized as having a crucial role as an energy carrier in this transition. The Port of Rotterdam in the Netherlands has set its goals on facilitating the transition by aiming to become the 'Hydrogen Hub' of Northwestern Europe. To reach this goal, the aim is set to transport 4.6 Mt of H₂ by 2030 and 20 Mt by 2050. This will be accomplished both by hydrogen production and with import. It is expected that by 2030, 2 to 2.5 GW of (low temperature alkaline or PEM) electrolysis capacity will be installed and the rest of the hydrogen will be imported in the form of ammonia. Electrolysis produces significant amounts of waste heat and due to the storage conditions of ammonia, there is potential for cold utilisation (which is unexplored in the field of ammonia cracking). Instead of wasting this thermal energy, it would be more useful to recover and use it. Thereby potentially increasing total system efficiency and contributing to the energy transition.

The aim of this study is thus to quantify the identified thermal waste streams from water electrolysis and ammonia cracking, in order to determine how these should be reused in different applications. This will be done by using the Port of Rotterdam as a case study.

A dynamic electrolyser model was made to calculate the waste heat output as a result of fluctuating operation (due to intermittency of wind energy). A steady state thermal analysis was made of an ammonia cracking plant. Not only to determine the quality and quantity of potential cooling streams, but also to observe the effect of adding thermal energy on the ammonia cracking process (at different temperature levels). The results from these models were then used to evaluate multiple relevant and novel applications. Electrolysis waste heat modelling is applied in district heating and integration in the ammonia cracking process. Cold utilisation has been evaluated for CO₂ and H₂ compression, and for industrial cold storage.

From the different considered applications, the largest amount of electrolysis waste heat that can be reused in a single application is with integration in the ammonia cracking process. Not only can almost all the heat be directly integrated, it also creates a synergy within the hydrogen industry. This application has distinct advantages compared to other applications studied in this thesis, making it a preferred option. After that, it has been demonstrated that electrolysis waste heat can be used to provide reliable heating for a district heating network. This application is highly socially relevant, but might be a more complex option to integrate all of the waste heat. Ammonia cracking cold utilisation concluded that from a technical perspective multiple use cases are possible, however the practical feasibility must be further investigated.

This study has started to explore the potential of cold utilisation and i.e. the integration of low temperature waste heat in the ammonia cracking process. The surface of this topic has been scratched and shows results that indicate the potential it has and the need for more detailed research in this field.