Full-spectrum solar energy utilization for green ammonia production via solid oxide electrolysis cell coupled with Haber-Bosch process

Ammonia is an important chemical commodity that is widely used for fertilizer production. The production of ammonia contributes to 1.2 % of the global carbon dioxide emissions. Solar production of green ammonia from nitrogen and water is essential for reducing the carbon emission. In this study, a novel full-spectrum solar ammonia production system is developed by integrating the solar-driven solid oxide electrolysis cell with the Haber-Bosch process. A novel parabolic dish consisting of wavelength-selective filter coated photovoltaic cells is designed to convert solar energy into electricity and heat for the solid oxide electrolysis cell. The effects of solar input, current density of solid oxide electrolysis cell, aperture diameter, and ammonia synthesis pressure on the system are studied. The results show that the solar to hydrogen efficiency is 27.5 %, corresponding to an operating temperature of 1130 K. A solar to ammonia efficiency of 15.6 % is achieved, which is 4.6 % higher than the state-of-the-art efficiency of solar-driven electrochemical synthesis of ammonia. By analyzing the Sankey diagram, the energy loss of photovoltaic cells and the heat losses contribute more than 63 % of the total solar input. This study provides a benchmark for solar-driven ammonia production.