2023-08-27 15:01:05
Jean Luc PONCIN
27.08.2023 at 17:00
In its latest report on safety in hydrogen production facilities, the National Energy Technology Laboratory (NETL) of the United States Department of Energy analyzed accidents in the sector since 2006. If human error represents 10% of the problems encountered, it is above all the hardware that is at the origin of the malfunctions.
If, until 2012, the vast majority of the approximately 200 incidents reported had taken place in the laboratory, the development of domestic and industrial applications of hydrogen over the past decade has resulted in the proliferation of production facilities at greater ladder. Consequently, the gas must be produced, transported and stored; significantly increasing the risk of accidents, as in any industrial process.
Hydrogen is more flammable than methane
One particularity, however: hydrogen is a smaller and lighter molecule than methane (which allows it to escape from equipment and be diluted more quickly in the air) but it also has a much wider flammability range. wider. The main resulting risk is leakage, which in extreme situations degenerates into fire, or even explosion.
« Specifically, while natural gas has a flammability limit of 5-15% by volume, hydrogen-air mixtures are flammable in the range of 4-75% hydrogen by volume. Combining this with the fact that the minimum ignition energy of hydrogen is on the order of 5% of that of natural gas, hydrogen-air mixtures present a significantly higher fire hazard than gas mixtures. natural-air “, according to the report of the NETL.
If the risk remains present, the NETL study is nevertheless reassuring. Of the 350 hydrogen-related incidents reported in the United States over the past 17 years, more than half occurred in the experimental phases (mainly in the laboratory until 2012). Through information provided on a voluntary basis to the government website H2Tools since its launch in 2006, the NETL has been able to identify the origin of accidents. Equipment failures were cited in 25.9% of 347 reports, compared to around 9.8% attributing them to human error
Among the equipment implicated in the accident reports, ” approximately half of reported incidents involved pressure vessels, pipelines and valve systems and, to a lesser extent, compressed gas cartridges, electrical problems and measurement sensor failures ».
Electricity at the origin of the majority of serious accidents
Beyond simple hydrogen leaks, the accidents resulting in the ignition of the gas were mainly caused by ” static electricity discharges from faulty or improperly grounded personnel or electrical equipment. »
Causes which must be the subject of increased vigilance by manufacturers. Because hydrogen fires tend to burn more intensely than fossil gas fires (including faster flames and more frequent explosions), leading to faster oxygen depletion in enclosed spaces and thus increasing the risk of ‘asphyxia.
A call for vigilance
Given the significant development of the sector, this study is a warning signal for the hydrogen industry with regard to the high flammability of the air-hydrogen mixture: since 2006 these accidents have injured around fifty people and caused 15 death.
While the hydrogen production industry is globally among those where safety procedures (from design to operation) are well mastered, the NETL ” hopes that this report will be a valuable resource for stakeholders in the development of future hydrogen projects and contribute to the construction of safe and sustainable bulk hydrogen and electricity generation infrastructure ».
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