Risk-Based Maintenance models for hydrogen systems: a review for the glass and aluminium industry

The urgent need to mitigate climate change has placed decarbonisation at the forefront of global energy policy. Among other sectors, industrial high-temperature heat is very energy-demanding (1280 Mtoe/year in 2018 (IEA, 2019)) and responsible for 1.1GtCO2/year of direct emissions (IEA, 2019). Hydrogen has the potential to play a pivotal role in replacing fossil fuels as the primary source of heat for the glass and aluminium industry sectors. In this context, the Horizon Europe project H2GLASS (advancing Hydrogen (H2) technologies and smart production systems TO decarbonise the GLass and Aluminium SectorS) was launched at the beginning of 2023. The target is to address the technical, economical, and safety-related challenges of decarbonising the glass industry by replacing natural gas with hydrogen as fuel to the furnace, as well as demonstrating the applicability of the findings to other sectors, such as the aluminium industry. The project includes 23 industry partners and six use-case demonstrations. In addition to focusing on technology development and economic feasibility analyses, there is a need to investigate the safety aspect, which is currently a bottleneck in the roll-out of hydrogen technologies. Hydrogen is classified as a dangerous substance: it is flammable and can be responsible for material degradation. One of the main issues related to its use is hydrogen embrittlement, which is the loss of ductility and strength due to the entry of atomic hydrogen into the metal lattice. Maintenance and inspection activities and procedures are crucial in preventing integrity loss of hydrogen systems and ensuring safe operations. In this perspective, maintenance should be considered to mitigate material degradation and to avoid loss of equipment integrity and consequent accidents. Over the last decades, different industry sectors have adopted several maintenance techniques and strategies. The Risk-Based Maintenance (RBM) methodology is analysed following the proposal to adopt the Risk-Based Inspection (RBI) methodology for hydrogen technologies (Campari et al., 2022). The RBM approach prioritises maintenance activities based on the associated level of risk to avoid unnecessary operations and to reduce shutdowns, lessening the overall costs. A questionnaire on the maintenance policies and approaches used for the glass industry has been distributed to the H2GLASS consortium. The survey aimed at identifying needs and knowledge gaps in the maintenance and inspection procedures when replacing natural gas with hydrogen as fuel for the furnace. This article presents a literature review of the RBM methodology for hydrogen technologies. Furthermore, the paper summarises the findings from the questionnaire shared with the H2GLASS partners and identifies the criticalities of applying RBM to the glass case. Changes to the maintenance and inspection policies are also suggested based on the combination of the survey findings and the RBM methodology review. KEYWORDS: Risk-Based Maintenance, Hydrogen safety, Glass Industry