- Practice · 5 marks
Hydrogen storage and infrastructure requirements
Short answer
Compressed gas (350–700 bar) and cryogenic liquid (−253°C) store H2; metal hydrides and ammonia are alternatives. Infrastructure includes production (electrolysis/reforming), compression, high-pressure tanks, pipelines/tube trailers, dispensing stations. Safety: flammable (4–75% in air), low ignition energy, embrittlement, invisible flame; requires detectors, ventilation.
Explain the methods of storing hydrogen. Describe the infrastructure needed for production, storage, transport and utilisation of hydrogen, and mention the safety concerns.
Hydrogen has a high energy per kg (120 MJ/kg lower heating value) but a very low density (0.084 kg/m³ at normal conditions), so storage is the main difficulty.
Storage methods
| Method | Condition | Remark |
|---|---|---|
| Compressed gas | 350–700 bar in carbon-fibre tanks | Most used in vehicles; about 40 kg/m³ at 700 bar |
| Liquid hydrogen | −253 °C in insulated tanks | 71 kg/m³; 30 % of the energy is lost in liquefaction and boil-off occurs |
| Metal hydrides | H₂ absorbed in alloys (LaNi₅, MgH₂) | Safe, compact but heavy, low mass percent |
| Chemical carriers | Ammonia, methanol, liquid organic carriers | Easy to carry, need a reaction to release H₂ |
| Underground | Salt caverns, depleted gas fields | Large seasonal storage |
Infrastructure
- Production: electrolysers with renewable power, SMR or gasification units; water supply; purification.
- Compression and storage: compressors, high-pressure tanks, cryogenic tanks, cavern storage.
- Transport: tube trailers, liquid tankers, dedicated pipelines or blending into natural gas pipes (limit about 10–20 %).
- Utilisation: refuelling stations for fuel cell vehicles, fuel cell power systems, hydrogen burners, industry (ammonia, refining, steel).
- Standards: codes, trained staff, leak detectors.
Safety
Hydrogen is colourless and odourless, leaks easily through small gaps, has a wide flammable range (4–75 % in air), very low ignition energy (0.02 mJ) and burns with an invisible flame; it also embrittles steels. So good ventilation, hydrogen sensors, flame detectors and approved materials are required.
✓ Answer checked by Claude Opus 5.5 (high effort)
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