Exergy and techno-economic evaluation of solar-driven coal gasification coupled CLHG cogeneration system

Abstract

To diversify the energy supply for the gasification process, as well as to improve the high carbon emission problem of coal combustion for heat supply in the conventional gasification process and to improve the performance of the gasification system, this work proposes a solar/autothermal gasification coupled with a chemical looping hydrogen generation (CLHG) system for the stable production of pure hydrogen and electricity with low-energy CO₂ capture. To evaluate and optimize the system more intuitively, a comprehensive exergy distribution analysis of the proposed system was carried out. The results show that the proposed system can achieve 47 % and 45.68 % of energy efficiency and exergy efficiency, and the exergy loss mainly comes from the solar collector and chemical looping reactor, which occupy 60.1 % and 21.3 % of the total exergy loss, respectively, and optimization recommendations are given. Analysis of the direct nominal irradiance (DNI) shows that the system has a carbon capture rate (CCR) of 97.6 % and a fuel energy savings rate (FESR) of 53.7 % which is 16.7 % higher than the reference system. The techno-economic analysis shows that the proposed system can achieve a levelized hydrogen cost of 1.71 $/kg, which validates the economic feasibility of the solar hydrogen production system.