Global energy system is moving towards a decarbonization path. The share of renewables in the power sector have been increased, but its intermittent character affects the reliability and management of the system. New technologies such as Power to Gas (P2G) provide an efficient management of the surplus renewable energy. Most P2G systems use electrolysis to produce hydrogen (H2). H2 is the foremost candidate to o?set and eventually replace the fossil fuels and it will play an important role in our energy system. Building a new hydrogen transport infrastructure demands a lot of time, effort, and investments. An alternative cost-effective and practical pathway, which is receiving significant attention, is the injection of H2 into the existing natural gas (NG) network. Several research studies have been conducted during the last decade. The work carried out, shows that H2 can be blended with natural gas at percentage of 5-20% vol. without or with minor modifications on the gas network. There are currently more than 46 pre-industrial pilot projects worldwide that are investigating the impact of H2 addition on existing natural gas infrastructure and appliances. This paper presents a critical review on safety and risk analysis of H2 hazards on the pilot projects. Several factors affecting safety need to be considered, for instance the impact of H2 on the gas grid and on the end user appliances. Hazards such as leakage and permeation, material degradation, hazard detection, fire and explosion have been studied in relation to the H2 addition. The key safety considerations, the risk analysis and assessment methods and techniques of hydrogen injection pilots and hydrogen infrastructure are summarized and reviewed.
Hydrogen enriched natural gas: a critical review on safety and risk analysis on pilot projects
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