Advanced Methods for the Quantitative Assessment of the Safety of Decarbonization Technologies

Abstract

Climate change presents an urgent global challenge, underscoring the need for effective decarbonization technologies to reduce greenhouse gas emissions and mitigate its impacts. Blue hydrogen plays a pivotal role in this transition, serving as a bridge between the continued reliance on fossil fuels—still essential to meet the current global energy demand—and the future large-scale adoption of renewable energy sources. Blue hydrogen production leverages techniques like Carbon Capture and Storage (CCS), which prevents carbon dioxide (CO2) emissions from entering the atmosphere, and liquid hydrogen (LH2) systems, which ensure the efficient storage and transport of hydrogen.

While these technologies offer significant environmental benefits by lowering emissions and securing energy supply, they also introduce substantial safety challenges with respect to humans, assets, and the environment. These challenges must be addressed to ensure a secure and sustainable energy transition. In CCS, CO2 poses threats due to its toxicity and the potential for two-phase releases, where a mixture of gas with solid dry ice particles can cause material erosion, cold embrittlement, and cold burns. Additionally, CO2 can reduce seawater pH, impacting the marine biota. Similarly, LH2 presents hazards such as high flammability and explosiveness, with its extremely low temperatures further exacerbating the risk of cold burns and material brittleness. These safety issues are critical to the successful implementation of blue hydrogen technologies and require careful consideration and management.

In this regard, the primary aim of this PhD thesis is to enhance knowledge in the field of safety of blue hydrogen decarbonization technologies, specifically focusing on atypical accident scenarios involving CCS and LH2 facilities. Given the breadth and complexity of this research topic, a multidisciplinary approach is adopted, emphasizing risk management approaches, performance evaluation of safety barriers, analytical and empirical modelling, resilience assessment techniques, and human reliability analyses.

To address the safety challenges posed by CO2 and LH2 in the context of blue hydrogen, this thesis evaluates the strengths and limitations of existing risk management approaches for emerging technologies, explores their applicability in novel settings, and develops advanced techniques for quantitatively assessing safety and resilience. The key contributions of this thesis include:

· Evaluation of the inherent safety within blue hydrogen value chains and identification of priorities for the safe development of the blue hydrogen value chain;

· Establishment of the current state of knowledge in risk assessment for the CCS value chain;

· Estimation of the potential consequences of high-pressure CO2 releases, both atmospheric and subsea;

· Analysis of experimental data related to LH2 releases in both aerial and underwater environments;

· Evaluation of the performance of safety barriers in LH2 bunkering systems;

· Development of models and approaches for assessing resilience in LH2 bunkering systems;

· Exploration of human errors that could impact LH2 bunkering systems.

A further issue preliminary explored concerns the identification of Natech (natural hazard-triggered technological) accident scenarios affecting CCS facilities.

This PhD study offers valuable insights into the safety challenges associated with blue hydrogen value chains, focusing particularly on CCS and LH2 systems. It explores both the potential and limitations of these technologies within the context of risk management, identifying and addressing key knowledge gaps. The research highlights the limitations of models currently used for quantitative risk assessment, demonstrating how integrating probabilistic approaches and innovative strategies can enhance safety evaluations. Additionally, it emphasizes the importance of resilience and human reliability in achieving a more thorough assessment of these emerging technologies. All the developed methodologies were tested in real-world case studies, showcasing their effectiveness. The findings are critical for advancing risk planning and management strategies, while also paving the way for future research, particularly in the areas of offshore CCS systems and the safe handling of LH2.