Essential to building the hydrogen economy will be transporting hydrogen at low cost. Shipping will connect green hydrogen production, which will be near cheap renewable power, to where the it will eventually be used.
Over short distances, pipelines are likely to be the most cost-effective way of transporting hydrogen in bulk. However, for longer distances, hydrogen will have to be moved by sea as liquid hydrogen, or as a liquid chemical carrier such as organic hydrogen, methanol or ammonia. So, ports and shipping have a critical role in enabling the hydrogen economy by upgrading their infrastructure and technology.
A key question for the maritime industry is the form that hydrogen is transported in. This is partly determined by economics, because the costs of transporting hydrogen (and its derivatives) are balanced between factors such as: the type of renewable energy used to produce hydrogen; transport distance; the cost of electricity for the packing and unpacking of the hydrogen product; and the end user requirements.
At present it seems most likely that hydrogen will be transported as a liquid hydrogen or ammonia. Both have their advantages and disadvantages, but both are more complex than transporting the fuels of today, such as LNG.
Liquid hydrogen is supercooled at atmospheric pressure to -237°C to turn it into a liquid, so it requires pressurised transport and is difficult to contain due to the small size of hydrogen molecules. It is also explosive on ignition.
Transporting hydrogen as liquid ammonia (NH3) may be a better option because it can be stored at the warmer temperature of -33°C, and produced using a simple chemical reaction. This means it needs a lot less cooling than liquid hydrogen, but the downside is that ammonia is extremely toxic.
The table below shows how hydrogen and ammonia compare to LNG, which is probably the closest comparison we have at the moment for bulk transportation of energy by ship.
Key properties of transitional fuels
|Natural gas (Liquefied
natural gas (LNG))
|Energy density (as liquid)
(at atmospheric pressure)
|Burns back if unconstrained,
less dense than air
much less dense than air
|Less easy to ignite,
less dense than air
|Largest liquid carrier (2023)
|circa 260,000 m3
|circa 1,250 m3
|circa 93,000 m3