Power-to-Hydrogen Systems: Modelling, Operation and Techno-economic Analysis

Renewable hydrogen production has emerged as a promising solution for decarbonizing challenging sectors and accelerating the transition to cleaner energy. Electrolysis-based power-to-hydrogen (PtH₂) systems are playing an increasingly vital role in this transition. However, the economic feasibility of PtH₂ systems remains a significant barrier to their widespread implementation, and effective planning and operation management strategies are necessary to overcome this hurdle.

For the purpose of operation research, this thesis examines the modelling of electrolyzers, which are the key components of a PtH₂ system. From an energy management perspective, the thesis emphasizes the importance of integrating variations in efficiency, thermal management, and state transition properties into the model. This comprehensive model provides a basis for further research and exposes the dynamic characteristics of electrolyzers during flexible operation.

PtH2 systems are categorized into on-grid and off-grid systems, each with different operational characteristics. On-grid PtH₂ systems are involved in power markets, which offer the opportunity to increase profits through cross-commodity arbitrage due to the flexibility of electrolyzers. As the on-grid PtH₂ system owner faces complex and fluctuating markets, the thesis offers data-driven frameworks to optimize the operation of an on-grid PtH₂ system in the presence of multiple uncertainties. Data-driven robust optimization is utilized, which is shown to outperform stochastic and robust optimization. Additionally, being connected to the grid enables the provision of grid services, which provides an alternative source of revenue. Offering frequency regulation services to the grid enhances the financial performance of on-grid PtH₂ systems.

Off-grid PtH₂ systems have a simpler decision-making process. Nevertheless, the newly proposed model reveals the operational limitations of electrolyzer dynamics. Safety issues and on/off properties hinder the uptake of renewable energy and result in a mismatch between wind turbines and electrolyzers in the studied system. The thesis proposes an operation framework that accounts for batteries to address this issue.

Based on the electrolyzer models and operation framework, the thesis investigates the optimal planning and economic assessment of on-grid and off-grid systems. The optimal sizing of on-grid PtH₂ systems can help increase the net present value of the project in on-grid settings. The thesis shows that the sizing strategies differ according to different operation objectives. Additionally, research on off-grid settings provides ways to reduce the levelized cost of hydrogen, taking into account the dynamical properties of the electrolyzer.

Overall, this thesis proposes a holistic decision-making framework for PtH₂ systems considering the modelling, operation, planning and economic evaluation. Such a framework is utilized in both on-grid and off-grid applications, which demonstrates its versatility. As PtH₂ systems are in their early stage and few realistic experiences are available, this research can be significant to pave the way for economic hydrogen production from renewable energy.