Revolutionizing Maritime Sustainability: Inside NUS's Groundbreaking Ammonia Engine Initiative
The National University of Singapore (NUS), a leading institution in engineering and innovation, has officially launched a transformative project aimed at developing near-zero-emissions ammonia marine engines. Announced on February 4, 2026, this initiative positions Singapore at the forefront of global efforts to decarbonize the shipping industry, a sector responsible for about 3% of worldwide carbon dioxide emissions. By harnessing ammonia—a carbon-free fuel at the point of combustion—researchers at NUS seek to overcome longstanding technical hurdles, paving the way for cleaner, more efficient vessels traversing international waters.
At the heart of this endeavor is the innovative In-Cylinder Reforming Gas Recirculation (IRGR) engine concept, which promises to enhance combustion efficiency while minimizing harmful byproducts. This project not only underscores NUS's commitment to sustainable technologies but also aligns with Singapore's ambitious Maritime Singapore Decarbonisation Blueprint, reinforcing the city-state's role as a global bunkering and maritime innovation hub.
The Imperative for Ammonia in Marine Propulsion
Ammonia (NH3), a compound widely used in fertilizers and chemicals, emerges as a frontrunner among alternative marine fuels due to its high energy density and lack of carbon content. Unlike traditional heavy fuel oil or marine gas oil, ammonia combustion produces no CO2, making it ideal for meeting the International Maritime Organization's (IMO) stringent net-zero emissions target by 2050. However, transitioning to ammonia-powered ships requires solving inherent combustion challenges, a mission NUS is tackling head-on through interdisciplinary research.
Singapore, handling over 37 million twenty-foot equivalent units (TEUs) annually at its port, stands to benefit immensely. The nation's strategic location and established infrastructure for fuel bunkering make it a natural testing ground for green marine technologies. This NUS project builds on prior demonstrations, such as the world's first ammonia bunkering trial in Singapore's waters in 2024, highlighting the country's proactive stance in maritime sustainability.
Overcoming Key Challenges in Ammonia Engine Technology
Current ammonia marine engines grapple with several obstacles: low flame speed leading to unstable combustion, high ignition energy requirements, and elevated emissions of unburned ammonia (NH3), nitrous oxide (N2O), and nitrogen oxides (NOx). These issues result in suboptimal thermal efficiency—often below 40%—compared to diesel engines exceeding 50%. Unaddressed, they hinder ammonia's scalability for large ocean-going vessels.
Past NUS studies, including publications in Joule (2025) and Nature Communications (2024), have laid the groundwork by modeling ammonia-hydrogen blends and pilot-ignition strategies. Yet, practical implementation demands integrated solutions like IRGR to bridge lab concepts to real-world prototypes.
Unpacking the IRGR Engine Concept: A Step-by-Step Breakdown
The IRGR (In-Cylinder Reforming Gas Recirculation) technology represents a paradigm shift in ammonia engine design. Here's how it works:
- Step 1: Ammonia Injection and Partial Oxidation – Excess ammonia is injected into a dedicated reforming cylinder where it undergoes partial oxidation, breaking down into hydrogen (H2)-rich syngas (a mixture of H2, CO, and other gases).
- Step 2: Gas Recirculation – This syngas is recirculated back into the main combustion cylinders, acting as a combustion promoter to accelerate flame speed and stabilize ignition.
- Step 3: Enhanced Main Combustion – The hydrogen enrichment boosts overall thermal efficiency to levels competitive with diesel, while diluting the mixture to curb NOx formation.
- Step 4: Exhaust Management – Reduced unburned NH3 and N2O emissions ensure compliance with stringent regulations, achieving near-zero greenhouse gas output.
Simulations from NUS research show IRGR reducing unburned ammonia to under 8 g/kWh even at 97% ammonia energy ratio, a leap forward for high-substitution operations.Learn more from NUS's official project page
Leadership and Expertise Driving the Project
Associate Professor Yang Wenming, Principal Investigator from NUS's Department of Mechanical Engineering, brings decades of expertise in advanced combustion systems. "Ammonia has been recognised as one of the most promising fuels... but current engines face significant challenges," notes Prof. Yang. Supporting him is Senior Research Fellow Dr. Zhou Xinyi, overseeing lab operations.
Overseeing broader efforts are Professor Silvija Gradecak, Vice Dean (Research and Technology) at CDE, and Professor Lee Poh Seng, Head of Mechanical Engineering. Their vision transforms theoretical models into deployable hardware, fostering talent in sustainable engineering.
Strategic Partnerships Fueling Innovation
This three-year initiative thrives on a robust consortium. Academic allies include Shanghai Jiao Tong University, Nanyang Technological University (NTU), and A*STAR's National Metrology Centre, providing complementary simulation and metrology expertise.
Industry heavyweights—Keppel Energy Nexus for energy integration, Daihatsu for engine manufacturing prowess, and American Bureau of Shipping (ABS) for certification—ensure commercial viability. Collaboration agreements signed at launch signal strong commitment.Explore ABS's role in maritime classification
- Keppel: Infrastructure scaling
- Daihatsu: Prototype fabrication
- ABS: Safety and regulatory compliance
State-of-the-Art Facilities at NUS CDE
Housed in a new dedicated laboratory on the College of Design and Engineering (CDE) campus, the project features an engine test room for full-scale trials, a control room for real-time monitoring, and specialized setups for combustion diagnostics and systems integration. These facilities enable iterative testing, from bench-scale reforming to engine dyno evaluations, accelerating prototype development.
Singapore's Leadership in Maritime Decarbonization
As Asia's top bunkering port, Singapore mandates net-zero fuels for new harbor craft by 2030. Initiatives like the Global Centre for Maritime Decarbonisation (GCMD) complement NUS's work, focusing on safety protocols for ammonia handling. Funded by the Singapore Maritime Institute (SMI), this project bolsters national R&D, attracting global talent and investment.
Stakeholders from the Maritime and Port Authority (MPA) attended the launch, affirming governmental backing. Professor Li Tie of SJTU emphasized: "It requires disruptive technologies and strong international cooperation."MPA's decarbonization blueprint
Global Impacts and Pathway to IMO 2050 Goals
With shipping's emissions projected to rise without intervention, IRGR-equipped engines could enable retrofits for existing fleets and newbuilds. NUS aims for a prototype by 2029, scalable to medium-speed engines (10-20 MW) common in container ships and tankers.
Benefits extend beyond emissions: cost-competitive green ammonia production via renewable-powered electrolysis could stabilize fuel prices long-term. Challenges like toxicity and infrastructure persist, but NUS's holistic approach—including plume modeling—mitigates risks.
Career Opportunities in Green Maritime Research
This project opens doors for engineers, researchers, and postdocs specializing in thermodynamics, fluid dynamics, and clean energy. NUS's ecosystem nurtures PhD students through hands-on prototypes, preparing them for roles in the burgeoning green shipping sector. Aspiring professionals can explore research jobs or postdoc positions to contribute to such innovations. For career guidance, visit higher ed career advice on AcademicJobs.com.
Photo by Axel Richter on Unsplash
Looking Ahead: Prototypes, Pilots, and Beyond
Over the next three years, expect milestones like computational validations, subscale demos, and full IRGR prototype testing. Success could catalyze ammonia adoption, reducing shipping's 1 billion tonnes annual CO2 footprint. As Prof. Gradecak states, it's "an important milestone for efforts to decarbonise the maritime sector."
In summary, NUS's ammonia marine engines project exemplifies how university-led research drives real-world change. Professionals and students eyeing impactful careers should connect via university jobs, higher ed jobs, or rate my professor for insights into NUS faculty. Share your thoughts in the comments below.