The WIR! CAMPFIRE – CF 10_5 project, funded by the German Federal Ministry of Education and Research (BMBF) under the “WIR! Wandel durch Innovation in der Region” programme, investigated the physical‑chemical behaviour of ammonia with a view to its use as a maritime fuel. The Institute for Safety Technology / Ship Safety e.V. served as the project’s lead partner and carried out the experimental work that forms the core of this report. The consortium, comprising several academic and industrial partners, collaborated to validate key safety parameters and to integrate them into simulation tools. The project was completed within the allocated budget and schedule, with the final report dated 11 December 2023.

The experimental programme focused on parameters that underpin safety concepts for ammonia handling, transport, storage and combustion. In particular, the team measured flame point, explosion limits, minimum ignition energy, minimum ignition temperature and gap width. The results show that the lower explosion limit of 14 mol % and the upper limit of 32.5 mol % are experimentally valid, although the terminology used in the literature is misleading. In contrast, the minimum ignition energy of 14 mJ was found to be unreliable, requiring repeated ignition attempts and thus deemed problematic. The minimum ignition temperature of 630 °C could not be confirmed, and the flame point was not observed, suggesting that ammonia may not possess a conventional flame point. The measured gap width of 3.18 mm was also not validated. These findings indicate that many safety parameters for ammonia are either unknown or not yet experimentally confirmed.

A key insight from the study is that ammonia does not burn directly. Instead, at sufficiently high temperatures it decomposes into nitrogen and hydrogen, and it is the hydrogen that subsequently combusts. Consequently, safety measures for ammonia must be designed with hydrogen behaviour in mind, even when only ammonia is present. The risk of explosion is strongly temperature‑dependent rather than concentration‑dependent; at lower temperatures typical of storage and transport, the risk is negligible. For ammonia‑based combustion engines, ignition must rely on the in‑situ generation of hydrogen through controlled decomposition. In high‑temperature applications, hydrogen slip may occur, raising concerns about greenhouse gas emissions, as hydrogen contributes to the atmospheric greenhouse effect. These results have implications for the classification of ammonia as a flammable gas, the design of explosion‑protection systems, and the development of emission limits for hydrogen slip.

The validated data were discussed with the German Federal Institute for Materials Research and Testing (BAM) to inform regulatory and safety standards. The project’s outcomes provide a foundational dataset that can be incorporated into computational fluid dynamics and safety simulation models, thereby enhancing the reliability of design tools for ammonia‑powered maritime systems. The work also identifies critical data gaps that will guide future research priorities within the consortium and the broader maritime safety community.