Assessment of hydrogen-based energy systems for a sustainable future

Abstract

Hydrogen-based systems are essential for transitioning to a sustainable and low-carbon future. They provide a clean, efficient, and versatile energy solution by utilizing hydrogen as a fuel, which produces only water as a byproduct when burned or used in fuel cells. Therefore, the current research explores innovative energy systems for hydrogen production and their integration into sustainable energy frameworks. Three advanced techniques for hydrogen generation are analysed, each leveraging renewable energy sources to reduce dependence on fossil fuels. The first system employs a thermochemical cycle to convert excess electrical energy into hydrogen, enabling efficient energy storage and utilization. After analysis of system 1, the results reveal that the system generates 0.36 kg/h of hydrogen, which is utilised via SOFCs to produce power and electricity. Additionally, 1002 kW of electricity and 3.6 kW of heating can be supplied via the developed system. The overall system can achieve energy and exergy efficiencies of 20.6% and 22.1%, respectively. However, the thermochemical cycle can achieve maximum energy and exergy efficiencies of 79.6% and 62.9%, respectively. The second system comprises a solar PV-driven AEM electrolyser for hydrogen production. Subsequently, the produced hydrogen is fed to the fuel cell for electricity. The system's performance based on different kinds of energy and exergy efficiencies has been examined for the Kuching and Kota Kinabalu cities. After the analysis, it is concluded that system 2 can produce a maximum hydrogen production rate of 0.29 kg/h at 0.19 kW/m2 global radiation for the Kuching city whereas, for the Kota Kinabalu city, the highest hydrogen production rate can be 0.26 kg/h at 0.25 kW/m2 global radiation. Furthermore, the system's overall energy and exergy efficiencies are evaluated as 5.1% and 5.4%, respectively. Also, the effect of current density on the hydrogen production rate is analysed, and the result suggests that the hydrogen production rate decreases with a rise in current density. The third system of the current study consists of a photoelectrochemical AEM reactor, which uses low-cost earth metal-based electrocatalysts to produce hydrogen. Like PV-assisted AEM electrolyser, the performance of the PEC AEM reactor is assessed for different operating conditions when utilized in two different cities, i.e., Kuching and Kota Kinabalu. It is concluded that system 3 can produce a maximum hydrogen rate of 0.25 kg/h in Kuching and Kota Kinabalu. Furthermore, it exhibits the same energy and exergy efficiencies for both cities, i.e., 9.1% and 9.6%, respectively. The study also finds that while the hydrogen mass flow rate increases with higher solar irradiation and illuminated areas, the overall energy and exergy efficiencies decline with larger photocathode illumination areas. After comparing the three systems, it is concluded that system 1 (thermochemical cycle-based hydrogen production) outperforms all the systems in terms of energy and exergy efficiencies. The proposed hydrogen production system, like thermochemical cycles and PEC AEM reactors, can be used for various sectors, enabling a cleaner, more sustainable energy ecosystem. The future applications can include energy storage and grid balancing, ammonia and fertilizer production, carbon capture integration, etc. The current study's results help researchers improve efficiency, reduce costs, and enhance the sustainability of the different hydrogen production and storage systems.