Potential impacts of ammonia/hydrogen on engine lubricants: A review
image: Roles of the lubricant and lubrication circulation system (in yellow) in a typical four-cylinder engine
Credit: Carole Doncoeur, Lucia Giarracca-Mehl, Perrine Cologon & Christine Mounaïm-Rousselle.
Researchers from IFP Energies nouvelles and Université d’Orléans have conducted a comprehensive review on the effects of ammonia and hydrogen as fuels on engine lubricants. Published in Frontiers in Energy, this review addresses the combustion characteristics, reactivity, and exhaust gas compositions of these fuels, raising questions about lubricant compatibility.
With the global push towards cleaner energy sources, ammonia and hydrogen have emerged as promising alternatives to traditional hydrocarbon fuels, especially for long-distance or off-road applications. These fuels are carbon-free but exhibit unique combustion properties and exhaust gas compositions, raising concerns about their compatibility with existing engine lubricants.
The review highlights that the use of ammonia and hydrogen can significantly affect engine lubricants through mechanisms such as lubricant degradation, elevated nitrogen oxide (NOx) levels, and water vapor interactions. It further explores their role in lubricant pollution and the formation of particulate matter emissions.
The review consolidates findings from experimental studies and literature on ammonia and hydrogen combustion. It evaluates their interactions with engine oils, emphasizing chemical stability and accelerated degradation pathways relative to hydrocarbon fuels.
The findings have significant implications for the automotive and energy sectors transitioning to sustainable fuels. Developing lubricants that withstand ammonia/hydrogen combustion challenges—such as nitration, oxidation, and water contamination—is critical for advancing engine technologies and emissions control.
This review was funded by IFP Energies nouvelles and involved collaboration with the Institut Universitaire de France. The full paper is accessible via https://journal.hep.com.cn/fie/EN/10.1007/s11708-025-1031-3. Future work aims to design lubricants optimized for ammonia/hydrogen combustion, including antioxidant and anti-nitration additives.