Ultrafine nanoparticles from decarbonised transport platforms: Reconstructing the analytical puzzle

An association between air pollution and respiratory disease has been described for decades, with toxicity seen to be related to the higher surface area of smaller particles. Emission of sub 23 nm particles (<23NPs) is therefore increasingly being realised as a major problem to tackle. While an end to the sale of conventional cars and vans, including hybrids, is predicted by 2035, heavy goods vehicles (HGV) and marine propulsion face several limiting factors on their speed of change. Decarbonised propulsion systems for heavy-duty vehicles and marine transport have been proposed as sensible viable options, but these are likely to push nanoparticle emissions towards these tiniest sizes.

The project focus is towards future emission standards, particularly particles smaller than 23 nm, below the limit of current regulations. Selection of feasible alternatives for future transport scenarios requires understanding their contribution to <23NPs emissions. The experimental work planned focuses on improving a fundamental understanding of phenomena under varied operating conditions, fuels, and lubricants representative of those used in future propulsion systems to move people and goods. A decarbonised (Ammonia/Methane, Hydrogen) platform for marine applications funded through EP/T025522/1 will be used. Renewable liquid and gaseous fuels and engine oil formulation changes and their effects on ultrafine particles will be investigated. Concentrations of sub-23 nm particles and the distribution of particle sizes will be cross-referenced with chemical composition, structure, and morphology to fill the knowledge gap, especially in terms of understanding their formation and aging mechanisms. Transmission electron microscopy (TEM), performed at the nanoscale and microscale Research Centre in Nottingham (nmRC), complements the multi-faceted diagnostic approach which will be developed to reconstruct the analytical puzzle of the composition and nature of the ultrafine nanoparticles. New lubricant oil formulations and fuel additives, provided by our industrial partner Lubrizol, will help to understand the impact of chemical formulation on sub-23NP emissions. Overall, the project aims to gather insights on soot nanoparticle formation using advanced characterisation tools. High resolution TEM (HRTEM) and 3D electron tomography (3DTEM) of soot samples has been developed by the applicant in collaboration with the nmRC at Nottingham University.