Ammonia – an assessment of potential environmental impacts including prevention and mitigation measures

Abstract

Ammonia (chemical formula NH3) is one of the most widely produced chemicals for industrial and agricultural uses. Ammonia has gained attention as a potential hydrogen and energy carrier, and low carbon substitute fuel for rail and maritime transport. The potential of ammonia for new use cases may lead to an increased footprint of potential environmental impacts. The physical and chemical properties of ammonia offer significant benefits for transportation and storage, but challenges remain due to its highly toxic nature and uses outside of dedicated industrial precincts. Ammonia is typically liquefied to increase density for ready storage and transportation. Unplanned releases of liquid ammonia will result in immediate environmental impacts. Unplanned releases may adversely affect receptor species in aquatic and terrestrial environments, human health, as well as the reputation of the responsible organisation. Dispersion of ammonia into the environment depends on factors that include mixture density, temperature, humidity, wind and wave action, and release mode and direction. Understanding the fate of ammonia is fundamental to adoption of effective mitigation measures. Consequently, it is necessary to understand the behaviour of ammonia in the environment, how unplanned releases can be minimised, and how they can be combatted, in order to appraise its suitability as a low carbon liquid transport fuel. This paper assesses the risks posed by ammonia spills, its fate in aquatic environments, and the applicability of available spill models. It also addresses management measures for the prevention and mitigation of spills noting the highly soluble and toxic nature of the chemical.