Fig. 8. (a) Cost breakdown of the total cost of nitric acid production, for the cases considered in Fig. 7. The ‘high’ case and ‘low’ case refer to a plasma generator cost of 0.90 € W⁻¹ and 0.05 € W⁻¹, respectively. Process capacity 100 t-HNO₃ day⁻¹, electricity cost 20 € MW h⁻¹. Oxygen is added to account for the lower oxygen content in air, as compared to the nitrogen content in air. At the process scale of 100 t-HNO₃ day⁻¹, about 1300 m³-O₂ h⁻¹ is required, which costs about 14–28 € t-HNO₃⁻¹.¹⁰⁶ The operational costs apart from the electricity cost is assumed to be 2% of the CapEx. (b) Effect of the energy consumption of the plasma-based NO_X synthesis process on the total cost of nitric acid production. The solid and dotted line represent the plasma process with a plasma reactor cost of 0.90 € W⁻¹ and 0.05 € W⁻¹, respectively. The orange square represents the total cost of nitric acid for a reference electrolysis-based Haber–Bosch process combined with an Ostwald process. Process capacity 100 t-HNO₃ day⁻¹, electricity cost 20 € MW h⁻¹.