Advancing Predictive Models for Ammonia Releases at Sea — ARISE WP5 Update

The ARISE project continues to make major strides toward improving safety and environmental preparedness for ammonia bunkering operations. A key focus of the initiative is Work Package 5, which is dedicated to developing and refining predictive models that simulate the behavior of ammonia releases at sea, both in near-field and far-field scenarios.

Objectives

Thought its WP5, ARISE aims to produce robust models that can predict how ammonia behaves when accidentally released in marine environments. These models will be key in interpreting the upcoming controlled sea trials and, more broadly, in guiding industry and regulators toward safer design and emergency response strategies.

Progress Highlights

Early 2025, a webinar was held to present the modelling strategy to the sponsors. This event fostered valuable dialogue and confirmed the alignment of technical priorities across stakeholders within ARISE.

Since then, the consortium has finalised Deliverable D5.2 (confidential), a comprehensive overview of the selected modelling tools. This document outlines the strengths and limitations of leading consequence models such as PHAST, DRIFT, GASP, and OSERIT — and introduces the rationale for linking them in a combined modelling chain. None of these tools alone can fully capture the complex interactions during an ammonia release, especially in the critical first seconds.

That is why the project has initiated the development of a dedicated near-field model that will feed into these existing tools, enhancing the accuracy of predictions across all time and spatial scales.

In parallel, technical discussions are ongoing among the modelling teams to define appropriate parametrizations for near-field releases of cold liquid ammonia, with special attention to flash evaporation, bubble dynamics, dissolution, and plume formation.

Preliminary Results

Early testing has confirmed the importance of simulating both atmospheric and aquatic processes, including:

• Ammonia dissolution and evaporation at the water surface

• Aerosol formation

• Vapour cloud transport in wind conditions

• Mixing and nitrification processes in the marine water column

These insights will significantly inform both the sea trial protocols and the interpretation of field data.

What’s Next?

The coming months will focus on finalizing the near-field model concept and selecting the most suitable implementation strategy. Once developed, the near-field model will be validated against the experimental data collected during the sea trials, enabling a full model chain for predictive analysis.

Comprehensive documentation will be published at the end of the project, detailing the methodologies, assumptions, and lessons learned during model development.