Can ammonia hold the key to decarbonisation?

In the transition to a low-carbon economy, ammonia is rising to prominence as a potential chemical energy carrier, with significant advantages over hydrogen. Anton Tvelenev and Dr Juan Gomez Prado from at KBR Consulting, explore the potential of this molecule to fuel progress towards cleaner, greener energy

- ABDULAZIZ KHATTAK

AMMONIA has garnered significant attention due to several factors, such as its ability to leverage existing ammonia trading infrastructure, lower transportation and handling costs compared to hydrogen and other potential low-carbon hydrogen carrier molecules, as well as its relatively high hydrogen mass content and lack of carbon in its molecular structure.

There are two major advantages of using ammonia over hydrogen. Firstly, ammonia boasts a higher volumetric energy density than hydrogen (with a LHV of 12.7GJ/cu m vs 4.7 GJ/cu m for hydrogen at 700 bar and 8.8 GJ/cu m for liquid hydrogen), albeit still inferior to most hydrocarbon fuels.

Thus, a switch to ammonia rather than hydrogen represents a smaller penalty when it comes to maximum energy storage volumes and the cost of such storage.

The second advantage of ammonia is the option to leverage existing ammonia global trade infrastructure.

Ammonia is a globally traded commodity with a well-established freight, storage, and transshipment infrastructure, certification, and operational standards.

In contrast, hydrogen distribution is presently confined to a few regional piped networks in the US and EU, or specific cluster site distribution networks serving various industrial consumers.

TECHNICAL CHALLENGES & KEY SAFETY CONSIDERATIONS

Ammonia, however, introduces a distinct set of safety risks compared to conventional fuels.

While it poses a lower fire and explosion hazard than hydrocarbon fuels, its toxic nature and hydrophilic, corrosive properties necessitate the development of entirely new safety protocols if it were to become one of the primary energy carriers for direct fuel use.

Fortunately, the fertiliser industry has accumulated a substantial body of safety knowledge that can be directly applied in this context.