(759a) Optimization of Renewable Ammonia Production Via Electrochemical Reactions

Ammonia (NH₃) synthesis accounts for nearly 2% of global energy consumption, mainly because the prevalent process for NH₃ production (the Haber-Bosch process) operates at a very high temperature and pressure. The greenhouse gases thus created have motivated the development of processes which operate at more mild conditions, and can be operated dynamically, employing only renewable energy from a dedicated solar or wind farm. This research project explores the design and operation of the production of ammonia via an electrochemical process. A novel integration of H₂ production, NH₃ synthesis and renewable energy sources is designed to achieve a green process and high energy efficiency. Hydrogen produced via water splitting is reacted with nitrogen, to create ammonia in a packed bed reactor. The plant is operated dynamically, such that the power required for electrolysis and compression can be obtained from renewable sources. The process was simulated using ASPEN, in steady-state and then dynamically to handle variations in renewable power availability. Energy storage systems provide an additional degree of freedom for the model. A mixed integer non-linear program (MINLP) model is then formulated to optimize the process by minimizing total energy consumption, and solved using DICOPT. Results show how varying levels of production and energy storage usage correspond to different levels of energy availability, and demonstrate the feasibility of completely sustainable ammonia production with no raw materials other than water and air, and zero emissions since all the power is renewable.