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Hydrogen production and storage

Short answer

Hydrogen is mainly produced by steam methane reforming or electrolysis (green hydrogen with renewable power). Storage options include high-pressure tanks at 3500–7000 bar, cryogenic liquid at -2533 °C, metal hydrides, or chemical carriers. Transmission uses pipelines, tube trailers, or liquid tankers.

Describe the production, storage and transmission of hydrogen fuel (hydrogen energy).

Production of hydrogen

Hydrogen is an energy carrier, so it must be produced from compounds containing it.

  1. Steam methane reforming (SMR): CH₄ + H₂O → CO + 3H₂ (700–1000 °C, nickel catalyst), then water-gas shift CO + H₂O → CO₂ + H₂. This is the most widely used method: natural gas gives about two-thirds of world hydrogen, and fossil fuels together (with coal gasification) give about 95% ("grey" hydrogen; with CO₂ capture it is "blue").
  2. Electrolysis of water: 2H₂O + electricity → 2H₂ + O₂. Alkaline, PEM or solid oxide electrolysers. If the electricity is from hydro, solar or wind, it is green hydrogen. Nepal's surplus hydroelectricity offers this potential.
  3. Coal gasification: coal + steam → syngas (CO + H₂).
  4. Biomass gasification / biological methods: gasification of biomass, and photobiological production and fermentation by algae and bacteria.
  5. Thermochemical water splitting (sulphur–iodine cycle) using high-temperature heat from solar or nuclear.
  6. Photoelectrochemical splitting using sunlight (research stage).

Storage of hydrogen

Hydrogen has high energy per kg but very low energy per volume, so storage is the main challenge.

  • Compressed gas: steel or composite tanks at 350–700 bar (used in fuel cell vehicles).
  • Liquid hydrogen: cooled to −253 °C in insulated cryogenic tanks; energy intensive and with boil-off losses.
  • Solid-state (metal hydrides): hydrogen absorbed in alloys (for example LaNi₅, MgH₂); safe, compact, but heavy.
  • Chemical carriers: ammonia, methanol, liquid organic hydrogen carriers.
  • Underground storage: salt caverns for large scale.
  • Adsorption on carbon nanotubes / porous materials (research).

Transmission (transport)

  • Pipelines: dedicated hydrogen pipelines or blending into natural gas networks.
  • Tube trailers (compressed gas trucks) and liquid tankers for medium distance.
  • Ships carrying liquid hydrogen or ammonia for long distance.
  • Pipeline transport is cheapest for large amounts; hydrogen needs materials resistant to embrittlement.
Source(H2O) -> Electrolyser -> Compress/Liquefy -> Store
          -> Pipeline/Truck -> Fuel cell/engine

✓ Answer checked by Claude Opus 5.5 (high effort)

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