Plug Power Inc (PLUG)

[B_B!]

the auto-ignition temperature of hydrogen is considerably higher than that of kerosene (550 °C vs 220 °C), also hydrogen is about 14 times lighter than air, so if spilled it quickly diffuses and the vapors rises and disperses, rather than accumulating at ground-level [17]. Since hydrogen is a gas that is already present in the atmosphere, a spillage would not represent an environmental hazard in the same way compared to a fossil fuel spill. The minimum ignition energy of hydrogen, however, is considerably lower than that of other carbon-based fuels, therefore, a weaker spark can cause ignition.
Moreover, the flammability range is wider meaning the concentrations in the air required to have a fire are wider for hydrogen (4-76%) than for kerosene (1.4-7.6%) [3]. On the other hand, the lower flammability limit is higher for hydrogen than kerosene (4% vs 1.4%). This means that if the concentration of kerosene in air is more than 1.4%, a fire can occur, however this number is 3 times larger for hydrogen. The hydrogen flame is invisible, and the gas is odorless making it difficult to detect leaks or to fight a hydrogen fire if it that cannot be seen. Since H2 is such a small molecule, leaking through cracks or pores is a possibility if the tank is not properly insulated, and this is associated to a higher risk due to the reasons outlined before, demonstrating that proper insulation is fundamental.

https://www.iata.org/contentassets/d13875e9ed784f75bac90f000760e998/fact_sheet7-hydrogen-fact-sheet_072020.pdf