Introduction: The Density Dilemma

We can produce green hydrogen with renewable energy, but there is a major hurdle: Hydrogen is the lightest element in the universe. While it has incredibly high energy per unit of mass, its volumetric energy density is very low.

Under normal atmospheric pressure, 1 kg of hydrogen gas occupies about 11 cubic meters—roughly the size of a small garden shed. To move it efficiently, we must “shrink” it, which is where the real challenges begin.

1. Physical Challenges: Compression vs. Liquefaction

To pack enough hydrogen into a tank for a truck or ship, we use two main methods:

• High-Pressure Compression: Gaseous hydrogen is squeezed into tanks at pressures of 350 to 700 bar (up to 10,000 psi). This requires specialized, reinforced tanks made of carbon fiber to handle the intense pressure.

• Cryogenic Liquefaction: By cooling hydrogen to -253°C (-423°F), it turns into a liquid, which is much denser than gas. However, this process is extreme; it requires roughly 30% of the energy contained in the hydrogen just to cool it down.

2. Infrastructure: The “Smallest Molecule” Problem

Hydrogen doesn’t just play nice with existing oil and gas infrastructure. It presents two unique technical hurdles:

• Hydrogen Embrittlement: Hydrogen atoms are so small they can actually seep into the molecular structure of steel pipes, making them brittle and prone to cracking. Existing natural gas pipelines often cannot carry pure hydrogen without expensive upgrades or special coatings.

• Leakage: Because it is the smallest molecule, hydrogen can leak through seals and joints that would be perfectly airtight for natural gas.

3. Transportation Methods

Depending on the distance and volume, different logistics are required:

4. Chemical Carriers: Ammonia and LOHCs

To avoid the high costs of liquid hydrogen, researchers are using “carriers” like Ammonia. Hydrogen is chemically bonded to nitrogen to create a liquid that is much easier to store and transport using existing shipping infrastructure. Once it reaches its destination, the ammonia is “cracked” to release the hydrogen back into gas form.

Conclusion

Solving the storage and transport puzzle is critical to the Levelized Cost of Hydrogen (LCoH). While we have the technology to move it, the goal for the next decade is to make these processes less energy-intensive and more affordable through dedicated “Hydrogen Backbones” and better material science.

Next Up: We’ve looked at how it’s made and moved. Now, where is it actually going? In Article 8, we explore: What are the main uses of hydrogen in industry today?