Life cycle assessment of nitrogen fixation process assisted by plasma technology and incorporating renewable energy

The importance of nitrogen fixation is evident in every aspect of a human being’s life -from the synthesis of vital for all organisms nutrients and, in turn, the ecosystem conservation to the production of fertilizers, plastics and many other daily usage products. However, increasing concerns about the environmental sustainability of contemporary chemical industry seem to impose, nowadays, great challenges to the industrial nitrogen fixation which is linked to immense energy consumption and burdened emissions profile. Upon these considerations, it becomes imperative to adopt a holistic approach towards the development of novel “green” process technologies for the synthesis of fixed nitrogen. A considerable effort to that direction has been made by means of plasma technology mainly at laboratory scale. Although research studies have shown promising results, little attention has been placed on conceptualizing plasma-assisted nitrogen fixation at an industrial scale and evaluating its environmental footprint. This issue is practically addressed in the present research work which focuses on the ex-ante process design of plasma-assisted nitric acid synthesis for a modular plant and the respective Life Cycle Assessment (LCA) incorporating renewable energy sources. In order to facilitate the analysis of the LCA study, a sensitivity analysis has been considered on the reaction yield, the plasma power consumption, the recycle of unreacted gas stream and the energy recovery in the plasma reactor. LCA results exhibit for the plasma-assisted nitric acid, incorporating the recycle of the tail gas and solar energy, an improvement in the Global Warming Potential of 20% as compared to the conventional production pathway.