Hydrogen Energy: Storage

A: Governing principle: At 350 bar and ambient temperature, hydrogen deviates from ideal gas behavior and requires a real-gas density. Applied here: NIST/GERG correlations give ~20–22 kg/m³ at 15 °C, so 1.2 m³ holds roughly 24–26 kg before operational losses. Distractor B traps engineers who know PV=nRT but forget compressibility at high pressure.

A: Governing principle: Hydrogen compatibility is governed by material strength and microstructure, not just pressure test margin. Applied here: High-strength carbon steels under cyclic hydrogen service face embrittlement and fatigue per industry guidance, independent of hydrotest results. Distractor D catches those who focus only on MAWP math and ignore damage mechanisms.

A: Governing principle: Even with high-performance insulation, LH₂ tanks experience non-zero heat ingress driving boil-off. Applied here: 0.2–1% of 5,000 kg gives tens of kilograms per day, not hundreds. Distractor B appeals to LNG intuition but ignores hydrogen’s lower density and different thermophysics.

A: Governing principle: Polymer liners allow molecular diffusion of hydrogen even without discrete leaks. Applied here: Passing pressure tests yet elevated ambient readings align with permeation plus inadequate ventilation. Distractor B explains pressure loss but not a clean decay test.