Green impacts of transforming green electricity into microwave for ammonia and urea production

Abstract

Green NH₃ production is challenged by high energy consumption, costs, and low yields. Here, we proposed a new green NH₃ process utilizing microwave (MW)-driven N₂ transformations (GreenE+MW). This process integrates water electrolysis, air separation, MW-assisted NH₃ synthesis, and NH₃ separation. For comparison, a green NH₃ process using the Haber–Bosch technology (GreenE+HB) was established, and the energy, economic, and environmental impacts were evaluated. The GreenE+MW process increased NH₃ yield by 25.14% and reduced energy consumption by 20.69% compared to the GreenE+HB process. Furthermore, it demonstrated notable advantages in cost and carbon footprint, with green NH₃ production costs potentially reduced to 326.84 USD/tNH₃ at electricity price of 0.02 USD/kWh. Based on which, a green urea process was proposed, achieving an 85% reduction in carbon emissions (0.128 kgCO₂e/kgUrea) compared to conventional methods. This work offers a unique electrification technology to reconstruct the industrial NH₃ and urea production processes with a lower carbon footprint.