# Hydrogen and hydrogen carriers: How it works

Squeeze it, chill it or lock it inside ammonia

Source page: https://www.materialinsights.org/energy/e_h2_transport/explain/

What this tab covers How the energy actually moves, step by step: the science that makes it work and the engineering that makes it practical.

Hydrogen is the lightest molecule, so it holds very little energy per litre unless it is squeezed, chilled to a liquid or locked inside another chemical. Each way of moving it is a trade between how much it can be packed and how much energy the packing costs.

#### Step by step

1. **Produce and condition**Hydrogen leaves an electrolyser or reformer as a gas at roughly 20 to 30 bar (1 bar is about normal air pressure). It is dried and cleaned, then either compressed, liquefied or reacted into a carrier such as ammonia.
2. **Pipeline (large flows, land)**Compressors push gas into a steel pipe at about 70 to 100 bar. Gas always flows from high to low pressure, so compressor stations along the route top the pressure back up. Existing natural gas pipes can be converted if their steel is suitable.
3. **Tube trailer (small flows, road)**For filling stations and small users, gas is compressed to 180 to 250 bar or more into bundles of steel or carbon-fibre cylinders on a lorry trailer, which is driven to site and swapped or emptied.
4. **Liquid hydrogen (road and sea)**Hydrogen is cooled to minus 253 C, where it becomes a liquid about 800 times denser than the gas, and carried in vacuum-insulated tanks on trucks or ships.
5. **Chemical carriers (long-distance sea)**Hydrogen is combined with nitrogen to make ammonia, or loaded onto a liquid organic hydrogen carrier (LOHC), shipped in ordinary chemical tankers, and released again at the destination by cracking or dehydrogenation if pure hydrogen is needed.

#### The science

Per litre at room pressure, hydrogen gas holds much less energy than natural gas, so all transport routes are about raising density. Compression to pipeline pressure shrinks the volume about 95 times and road pressures of 350 to 700 bar about 290 to 500 times; liquefaction gives nearly 800 times, and ammonia about 1,800 times (it is liquid at minus 33 C, or at 7.5 bar at 20 C). The small hydrogen molecule also slips into steel and can make high-strength pipe brittle, which is why repurposing needs metallurgical checks, and it leaks through gaps that would hold methane.

#### The engineering

Pipelines use carbon-steel pipe and compressors, but because hydrogen carries about a third of the energy of methane per cubic metre, the gas must flow at three to four and a half times the volume of natural gas, and pipeline compressors spin at roughly 10,000 to 23,000 rpm against about 3,000 to 10,000 rpm for natural gas. Tube trailers use Type 1 steel tubes (about 380 kg of hydrogen) or lighter composite vessels (560 to 900 kg). Liquid hydrogen needs double-walled vacuum tanks and boil-off handling; the first ship, Suiso Frontier, carried 1,250 cubic metres. Ammonia uses refrigerated or pressurised tanks already common in the fertiliser trade, with about 170 ammonia port terminals in operation.

#### Key numbers
 Pipeline pressure 70 to 100 bar^[3](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2022/Apr/IRENA_Global_Trade_Hydrogen_2022.pdf) Tube trailer pressure 180 bar or more (US limit 250 bar; exemptions allow 500 bar or more)^[4](https://www.energy.gov/cmei/fuels/hydrogen-tube-trailers) Hydrogen per tube trailer About 380 kg (steel) or 560 to 900 kg (composite); one maker claims up to 1,100 kg per module^[4](https://www.energy.gov/cmei/fuels/hydrogen-tube-trailers)^[5](https://hexagonpurus.com/our-solutions/infrastructure/hydrogen-distribution-systems) Liquid hydrogen temperature Minus 253 C^[6](https://www.csis.org/analysis/exploring-hydrogen-midstream-distribution-and-delivery) Ammonia liquefies at Minus 33 C at 1 bar, or 7.5 bar at 20 C^[3](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2022/Apr/IRENA_Global_Trade_Hydrogen_2022.pdf) Largest liquid hydrogen ship ordered About 40,000 cubic metres (32 times Suiso Frontier)^[7](https://h2-tech.com/news/2026/01-26/kawasaki-heavy-industries-to-build-world-s-largest-40-000-m3-liquefied-hydrogen-carrier/) Announced hydrogen pipelines to 2035 Over 40,000 km, of which about 9% operating or committed^[1](https://www.iea.org/reports/global-hydrogen-review-2026/trade-and-infrastructure)

#### Sources

1. [Global Hydrogen Review 2026: Trade and infrastructure](https://www.iea.org/reports/global-hydrogen-review-2026/trade-and-infrastructure) IEA, 2026
2. [Global hydrogen trade to meet the 1.5C climate goal: Part II, Technology review of hydrogen carriers](https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2022/Apr/IRENA_Global_Trade_Hydrogen_2022.pdf) IRENA, 2022
3. [Hydrogen Tube Trailers (first published 2015, updated June 2026)](https://www.energy.gov/cmei/fuels/hydrogen-tube-trailers) US Department of Energy, 2026
4. [Hydrogen distribution systems (product page; capacity is a company claim)](https://hexagonpurus.com/our-solutions/infrastructure/hydrogen-distribution-systems) Hexagon Purus, 2026
5. [Exploring the Hydrogen Midstream: Distribution and Delivery](https://www.csis.org/analysis/exploring-hydrogen-midstream-distribution-and-delivery) CSIS, 2023
6. [Kawasaki Heavy Industries to build world's largest 40,000 m3 liquefied hydrogen carrier](https://h2-tech.com/news/2026/01-26/kawasaki-heavy-industries-to-build-world-s-largest-40-000-m3-liquefied-hydrogen-carrier/) H2 Tech, 2026

## Other sections

- [Summary](https://www.materialinsights.org/energy/e_h2_transport/index.md)
- [Overview](https://www.materialinsights.org/energy/e_h2_transport/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_h2_transport/correlation/index.md)
- [Efficiency and losses](https://www.materialinsights.org/energy/e_h2_transport/efficiency/index.md)
- [Technology advances](https://www.materialinsights.org/energy/e_h2_transport/advances/index.md)
- [Value chain](https://www.materialinsights.org/energy/e_h2_transport/valuechain/index.md)
- [Geopolitics and regulation](https://www.materialinsights.org/energy/e_h2_transport/geopolitics/index.md)
- [Unit economics](https://www.materialinsights.org/energy/e_h2_transport/economics/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_h2_transport/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_h2_transport/links/index.md)