As a direct result of the fundamental work undertaken on the MariNH3 research programme at University of Nottingham, the Nottingham team, working with a consortium of industrial partners, successfully secured two additional Innovate UK funded grants under Round 4 and Round 6 of the Clean Maritime Demonstration Competition (CMDC):

  • ENTICE (10096979), April 2024-March 2025: investigated the incorporation of a thermally recuperated ammonia cracker within a multi-cylinder engine.
  • REACT (10159282), September 2025-March 2026: aims to deliver a laboratory-scale pre-demonstration of a single fuel ammonia genset with near-zero tailpipe emissions of unburned ammonia (slip)and NOx.

This subsequent funding has enabled the translation of insights from the fundamental MariNH3 studies into a lean operating strategy, supporting the progression of the technology from TRL 1 to TRL 4 and strengthening the pathway toward real-world maritime applications.

Volvo D8 Penta engine

Volvo D8 Penta engine at UoN with ammonia and integrated electric cracker for producing hydrogen from ammonia.

Challenges and solutions

Unburned ammonia and oxides of nitrogen (NOx) are a critical emission obstacle preventing the adoption of ammonia powered gensets.

While these emissions can be simultaneously reduced with a mature after-treatment system like Selective Catalytic Reduction (SCR), the effectiveness of the after-treatment system is dependent upon the composition of unburned ammonia and NOx entering the SCR. Ideally, the ratio of unburned ammonia to NOx should be 1, which our operating strategy conceived from the initial studies funded by MariNH3 and which was achieved through co-fuelling with hydrogen.

The ENTICE project validated that the required hydrogen can be produced using a thermochemical ammonia cracker fed with pre-heated ammonia using the exhaust heat. The ongoing REACT project aims to validate the operating strategy with an SCR, and to scale the system to run a 200kW engine with ammonia as a single fuel and near-zero tailpipe emissions of unburned ammonia or NOx.

Impact

This research has generated valuable experimental data, published through Open Access platforms, to validate numerical models capable of assessing diverse combustion pathways. These models enhance understanding of emission formation processes within internal combustion engines.

The work has also demonstrated the feasibility of operating an internal combustion engine on single-fuel ammonia with near-zero tailpipe emissions of both unburned ammonia and nitrogen oxides, bringing the vision of a zero-emission ammonia engine significantly closer to reality. Ongoing research is focused on laboratory-scale demonstrations, with future funding expected to support the development of a full pilot-scale system.

Knowledge generated through the MariNH3 programme has also led to the creation of BlueDrive Propulsion, a new spin-out company at Nottingham. The company partners with operators of stationary power engine gensets to retrofit green ammonia co-firing capabilities to existing natural gas engines.