(514f) Nitrogen Fixation Using Microplasma Reactors for Local Production

Although nitrogen (N₂) makes up 78% of the Earth's atmosphere, it is chemically inert and cannot be directly used by most living organisms. It must first undergo nitrogen fixation, a process that breaks the strong triple bond in N₂ and converts it into reactive compounds such as ammonia or nitrates. Furthermore, the Covid pandemic and the crisis of several critical global supply chains has led to a revivification of thinking about more self-supporting manufacturing using supply of fertilisers at a distributed rather than at a central scale; experts call it ‘fractal economy’. This paper discusses the feasibility of local nitrogen fixation, as opposed to large-scale plants. Particularly, it presents three case studies that demonstrate how plasma technology can be applied to enable and intensify nitrogen fixation processes for local production. The first case focuses on developing a novel micropyramid-disk plasma reactor operating in micro-arc mode for ammonia (NH₃) production. Using a Ru/MCM-41 catalyst, ammonia was synthesized from N₂ and hydrogen (H₂) at atmospheric pressure. The microplasma reactor minimizes the gap between two electrodes, enhancing electric field strength and generating high-energy electrons to activate the reactants. This microstructured environment significantly boosts synthesis performance and opens new operating windows for small-scale ammonia systems. The second case explores non-thermal microplasma reactor (‘plasma bubble reactor’) to generate both ammonia and nitrate in the presence of water. This process generates plasma-activated water (PAW), a ready-to-use fertigation solution. Both air and nitrogen plasmas were tested, with catalytic configurations varied to optimize plasma-catalyst synergy. By implementing a recycling loop, the system increased nitrogen fixation yields by up to 70% compared to non-catalytic approaches, offering a practical path toward sustainable fertilizer production. The final case examines plasma-assisted artificial urine decomposition for nitrogen fixation in a plasma bubble reactor. Combining plasma activation with urease enzyme catalysis, the system converts urea into ammonium, nitrate, and nitrite with significantly improved efficiency. Urine mixtures contain not only urea but also other nitrogen-containing compounds capable of generating ammonium. The results show that plasma processing of urea in the presence of organic nitrogen compounds significantly enhances nitrate and ammonium yields, indicating improved urea conversion efficiency. Particularly, air plasma treatment of a mixture of urea, glycine, and creatinine results in a nitrate yield of almost 800 mg/L. Finally, it provides a comprehensive set of arguments for economics and environmental benefits on a local fertiliser production, based on co-financing and co-creation of value.