Production of Ammonia from Hydrogen Obtained in an Electrolysis Pilot Plant Powered By Energy from Geothermal Sources

Ammonia has been industrially synthesized since 1908 and has valuable applications in industries such as agribusiness, pharmaceuticals, textiles, refrigerants, plastics, and explosives. However, traditional production methods, such as methane steam reforming, are highly polluting due to greenhouse gasses emissions (CO and CO2). Therefore, this study evaluates the feasibility of environmentally low-impact ammonia production through the Haber-Bosch synthesis, as illustrated in Figure 1. This proposal integrates geothermal energy to supply the required power for 1) the ammonia synthesis stage and 2) the production and purification of synthesis stage reactants: N2 and H2. The aforementioned energy source has been chosen for its sustainability and constant availability. The identified geothermal reservoir, located in the Paucarani District, Tacna, Peru, has a theoretical power supply of 61.1 MW for 37 years, calculated using the volumetric method. Based on its characteristics, such as temperature and flow rate of the manifestations, the implementation of a simple flash power plant is proposed. Regarding H2 production, an electrolysis process with minimal carbon emissions has been proposed.

Consequently, to generate the results, material and energy balances were conducted in DWSIM and Python. An analysis of scenarios was performed in the mentioned software to obtain the amount of ammonia produced from a specific water consumption and the number of required wells, each with a power output of 1.5 MW. It is noteworthy that under the proposed design, 1 well is required to obtain 2.57 kmol/h of NH3 at 99.55% mol, based on a feedstock of 350 kg/h of water and 1050 kg/h of air. As a preliminary result, it was found that it is possible to power the processes involved in ammonia synthesis using geothermal energy, considering the streams described for the design of a pilot plant. Finally, for future research, it is recommended to consider the alternative of including a reverse osmosis plant to obtain the water entering electrolysis, as well as to assess the feasibility of scaling up the process.