Mitigating risks in ammonia handling

In this special report, Eric Sensat, Nikkiso Clean Energy & Industrial Gases Group, US, considers the specific safety considerations required in ammonia handling in pump technology.

As the energy transition gains momentum and expands in different directions, operators are finding the versatility of hydrogen can feature strongly in many applications. Its challenges – especially with regard to transport – are well documented and therefore ammonia’s role as a hydrogen carrier is becoming increasingly important due to its comparatively established supply chain.

As a result, ammonia leads among announced low-emissions hydrogen trade projects globally, and that trade could underpin over 40% of announced low-emissions hydrogen volumes by 2030 if all projects materialise.¹ Furthermore, estimates suggest ammonia’s power generation and hydrogen-carrier demand will reach more than 100 million tpy by 2055.² It is clear that demand for ammonia will increase, as will the scale of the projects required to produce, store, and transport it.

Risks of ammonia leaks

However, the associated risks of ammonia as a hydrogen carrier or as fuel in its own right require specific consideration. Both the IMO – for marine applications in particular – and safety organisations worldwide like OSHA have guidelines setting out the recommended approach in handling ammonia due to its toxicity. Ammonia is immediately dangerous to life or health (IDLH) at just 300 ppm, and while all hydrocarbons and molecules come with their own inherent risks, ammonia requires specific equipment and responses due to its characteristics. As demonstrated by the Desert Tortoise and Jack Rabbit experiments, driven by the US Department of Defence and Department of Homeland Security between 1983 and 2016, an ammonia leak would not simply evaporate and dissipate to the atmosphere, but would create a heavy mist that would be severely toxic over a significant downwind distance.

These risks become more pertinent when, as mentioned above, ammonia projects become larger and more complex in scale. It means that unlike other molecules, ammonia comes with an additional set of risks and therefore mitigations when considering the appropriate handling.

Minimising operational risks

In pumping technology, the crucial point is in the barrier between the pump itself and the motor. Should this barrier fail, ammonia will leak to the atmosphere. Therefore, seal-less pump alternatives should be considered to remove this risk. Furthermore, by removing the seal, additional equipment including the seal gas system are no longer required, removing further failure points with the pump motor submerged and cooled by the pumped liquid itself and no cable conduit or N₂ purge line running down to the motor.

Accompanied by the appropriate material compatibility – replacing standard copper or bronze pump components like wear rings, motor stator windings, cables, and terminal pins with ammonia-resistant materials – this approach ensures minimal risks of both leaks and accelerated corrosion in the pump.

Mitigating maintenance risks

Combined, these technologies reduce the need for service and maintenance – however these operations come with their own specific risks in ammonia handling. As the pump is submerged, ensuring it is removed from the ammonia completely flushed and decontaminated is key. Hermetic foot valve locks can isolate the tank before withdrawal, so the pump itself is ammonia-free by the time it reaches the maintenance bay after full decontamination through a decontamination vessel.

As the ammonia market gathers pace and projects become ever more complex and large scale, matching that growth with rising confidence in its safety is crucial. The appropriate risk mitigations in the applied pumping technology mean operators will rely on more than just one point of failure – reducing leaks and environmental hazards.

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