Modeling of PEM electrolyzer and ammonia production using Aspen plus

Abstract

Hydrogen is often portrayed as the future energy carrier. Among various hydrogen production techniques, water electrolysis is expected to be the most eco-friendly. The most promising method for producing pure and efficient hydrogen from renewable energy sources is PEM water electrolysis, which emits just oxygen as a byproduct and no carbon emissions. However, owing to overwhelming economics electrolysis is used for only 5 % of global hydrogen production. This study provides an Aspen Plus flowsheet model of the PEM electrolyzer system. The operational temperature, pressure, and power are used as simulation input. The anode side of a PEM stack is where most of the water circulation occurs. In a typical operation, some water will go from the anode to the cathode along with the H2 that is created. To keep hydrated, some water is recycled to the cathode side. When the power input is low and the electro-osmotic migration is minimum, the cathode pressure must be restricted to guarantee that water only flows from the anode to the cathode. This research suggests a recent setup for producing pure ammonia by utilizing pure hydrogen generated via renewable energy sources. Using the commercial programs Aspen Plus, the suggested system is simulated, and the findings are thoroughly analyzed. The developed system is examined in several operational scenarios. To thoroughly explore the ammonia production method and determine the impact of temperatures and pressures on the ammonia manufacture capacity, stoichiometric reactors have been used in aspen plus. Approximately 112,261.44 tons of green NH3 are produced on an annual basis. An economic assessment of PEMEL was conducted, focusing on determining the technology's payback period based on various economic assumptions. From a broader perspective of the green NH3 plant, the total installation cost was calculated to be $207.87 million, while the operational costs amounted to $194.76 million. Additionally, the total annual sales of ammonia and oxygen gas were calculated to be $294.29 million. These figures were derived based on the assumption of an electrolyzer cost of 1,000 $/kW in 2022 and an electricity cost of 0.04 $/kWh.