Exergoeconomic analysis and optimization of a concentrated sunlight-driven integrated photoelectrochemical hydrogen and ammonia production system

Abstract

The study presented here concerns a comprehensive investigation on exergoeconomic analysis and optimization of an integrated system for photoelectrochemical hydrogen and electrochemical ammonia production. The present integrated system consists of a solar concentrator, spectrum-splitting mirrors, a photoelectrochemical hydrogen production reactor, a photovoltaic module, an electrochemical ammonia production reactor and support mechanisms. Detailed thermodynamic and exergoeconomic analyses are initially conducted to determine the performance of the integrated system namely; efficiency and total cost rate. The obtained performance parameters are then optimized to yield the minimum cost rate and maximum efficiency under given constraints of the experimental system. The highest capital cost rates are observed in the photoelectrochemical hydrogen and electrochemical ammonia production reactors because of high procurement costs and electricity inputs. The optimized values for exergy efficiency of the integrated system range from 5% to 9.6%. The photovoltaic and photoelectrochemical cell areas and solar light illumination mainly affect the overall system efficiencies. The optimum efficiencies are found to be 8.7% and 5% for the multi-objective optimization of hydrogen production and integrated ammonia production system, respectively. When the exergy efficiency of the integrated system is maximized and the total cost rate is minimized at the same time, the total cost rate of the system is calculated to be about 0.2 $/h. The cost sensitivity analysis results of the present study show that the total cost rate of the system is mostly affected by the interest rate and lifetime of the system.