Addressing sustainable energy intermittence for green ammonia production

This work aims to study the production of Green Ammonia (Green-NH3) from a plant solely powered with Renewable Energy (RE) sources. The main current challenge of green ammonia plants is dealing with the energy intermittency and unpredictability of RE sources while ensuring a steady state ammonia production to avoid damaging the non-flexible Haber Bosch (HB) catalytic reactor. This work delivers a novel Techno-Economic (TE) modeling approach aiming to optimize the design and operation of a pilot-scale G-NH3 plant. The proposed TE model takes into consideration the intermittency of the RE sources, by considering different site locations with consistent yearly meteorological data. Additionally, to ensure a continuous power supply to the HB reactor, the model uses an original Energy Management Strategy (EMS) to adequately dispatch power available from the RE sources to Charge/Discharge Energy Storage Systems (ESS). The TE performances of the plant were evaluated by considering two main Key Performance Indicators (KPIs): HB Load Factor (LF) and Levelized Cost of Ammonia (LCOA). The results of this study indicated that the implemented EMS allowed to efficiently reduce the fluctuation of the RE sources by adequately allocating the available power to different time slots, which consequently increased the HB LF by 56% to 65%, depending on the type of the RE configuration. Consequently, this increase in the LF lead to a reduction of the overall cost of the plant, as the increase on production yield overweight the investment and operational costs increase. The PV/Battery scenario was found to be the most optimal plant entailing 6 MW of PV coupled to 11 MWh of Battery capacity with a LCOA of 774 $/tNH3. Finally, a forecast estimate projected between 2021 and 2050, predicted a potential cost reduction down to 250 $/tNH3, and suggests that by the year 2030, green ammonia is expected to be economically competitive with the conventional fossil-fuel based processes.