Blended natural gas/hydrogen fuel gas systems: An evaluation of risk

Abstract The addition of renewably produced (“green”) hydrogen to existing natural gas pipeline systems presents an effective means of transmitting energy with a reduced overall carbon footprint while granting end‐users access to federal incentives, a product of recent climate legislation. Although the concept of blended hydrogen/natural gas infrastructure is not new, it presents a host of engineering challenges that merit attention before being put into practice. In consideration of dissimilarities in physical properties and combustion characteristics between natural gas and hydrogen, the safe implementation of converted utility systems demands a comprehensive assessment of risks involved, including both the probability of accidental leak (infrastructure durability, pipeline embrittlement, and increased leakage rate through permeable elastomer seals) and the impact following the release of material. In this article, hazard analysis considering the effects of loss of containment for natural gas/hydrogen blend composition scenarios (0–30% H 2 by volume) is undertaken, specifically examining jet fire thermal radiation, flammable vapor dispersion, and vapor cloud explosions for fixed leak sizes. This investigation applies analytical techniques to evaluate the consequences of gas release behavior through vapor cloud dispersion and mixture deflagration simulation. The work aims to identify and quantify hazard severity and risk associated with system retrofitting for hydrogen blending within existing natural gas distribution networks.