Ammonia as a hydrogen carrier
Hydrogen plays a crucial role in decarbonising the European economy because it offers a versatile and clean energy carrier that can replace or complement fossil fuels in various sectors.
The European Union has recognised hydrogen’s potential as a key element in achieving its climate goal of becoming carbon-neutral by 2050, as outlined in the European Green Deal.
The hydrogen storage, transport and infrastructure challenge
Storage and transportation
Hydrogen has low energy density by volume, which means it needs to be stored and transported at high pressures or extremely low temperatures, both of which require energy and can lead to safety concerns.
Infrastructure
Current infrastructure is not well-suited for handling hydrogen. Retrofitting existing pipelines and transportation networks for hydrogen could be costly and logistically challenging.
The role of ammonia
The ammonia industry is already a large producer and user of hydrogen, and has substantial experience in handling large volumes.
Ammonia has a higher energy density compared to liquid hydrogen, making it a more compact and practical option for long-distance transportation and storage. Hydrogen must be compressed to between 350 and 700 times atmospheric pressure in gas form, or cryogenically cooled to -253°C as a liquid. Ammonia is denser and only requires compression to ten times atmospheric pressure or chilling to -33°C.*
Ammonia is an efficient hydrogen carrier due to its high hydrogen content (17.6 per cent by weight) and its ability to release hydrogen through a reversible chemical reaction.
Using ammonia as a hydrogen carrier in liquid form at relatively low pressures (around 8 atmospheres of pressure at 20 degrees) has the advantage of an energy density three times that of compressed hydrogen and 1.5 times that of liquefied hydrogen. Using ammonia to export hydrogen long distances, therefore, requires far fewer ships to transport the same amount of energy.
The volumetric energy density of a range of fuel options
Hydrogen content
Ammonia has a relatively high hydrogen content by weight, making it an attractive option for transporting and storing hydrogen.
Existing infrastructure
Global ammonia production infrastructure is well-established, with significant facilities already in place for its production, handling and transportation.
Liquid at ambient conditions
Ammonia is a liquid at moderate pressures and ambient temperatures, which can simplify storage and transportation compared to gaseous hydrogen.
