Energy Reports 8 (2022) 13793–13813 Contents lists available at ScienceDirect Energy Reports journal homepage: www.elsevier.com/locate/egyr Review article An overview of water electrolysis technologies for green hydrogen production S. Shiva Kumar a , Hankwon Lim a,b,c ,∗ a Carbon Neutrality Demonstration and Research Center, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-up, Ulju-gun, Ulsan 44919, Republic of Korea b Graduate School of Carbon Neutrality, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-up, Ulju-gun, Ulsan 44919, Republic of Korea c School of Energy and Chemical Engineering, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-up, Ulju-gun, Ulsan 44919, Republic of Korea article info Article history: Received 21 July 2022 Received in revised form 21 September 2022 Accepted 6 October 2022 Available online 25 October 2022 Keywords: Green hydrogen production Alkaline water electrolysis Anion exchange membrane water electrolysis Proton exchange membrane water electrolysis Solid oxide water electrolysis abstract Decarbonizing the planet is one of the major goals that countries around the world have set for 2050 to mitigate the effects of climate change. To achieve these goals, green hydrogen that can be produced from the electrolysis of water is an important key solution to tackle global decar- bonization. Consequently, in recent years there is an increase in interest towards green hydrogen production through the electrolysis process for large-scale implementation of renewable energy- based power plants and other industrial, and transportation applications. The main objective of this study was to provide a comprehensive review of various green hydrogen production technologies especially on water electrolysis. In this review, various water electrolysis technologies and their techno-commercial prospects including hydrogen production cost, along with recent developments in electrode materials, and their challenges were summarized. Further some of the most successful results also were described. Moreover this review aims to identify the gaps in water electrolysis research and development towards the techno-commercial perspective. In addition, some of the commercial electrolyzer performances and their limitations also were described along with possible solutions for cost-effective hydrogen production Finally, we outlined our ideas, and possible solutions for driving cost-effective green hydrogen production for commercial applications. This information will provide future research directions and a road map for the development/implementation of commercially viable green hydrogen projects. © 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Contents 1. Introduction................................................................................................................................................................................................................... 13794 2. Hydrogen production ................................................................................................................................................................................................... 13794 2.1. Significant role of green hydrogen in energy transition............................................................................................................................. 13795 3. Water electrolysis ......................................................................................................................................................................................................... 13795 3.1. Alkaline water electrolysis ............................................................................................................................................................................ 13796 3.1.1. Working principle of alkaline water electrolysis ......................................................................................................................... 13796 3.1.2. Cell components of alkaline water electrolysis ............................................................................................................................ 13796 3.1.3. Research and development of alkaline water electrolysis .......................................................................................................... 13797 3.2. Anion exchange membrane (AEM) water electrolysis ................................................................................................................................ 13798 3.2.1. Working principle of AEM water electrolysis ............................................................................................................................... 13799 3.2.2. Cell components of AEM water electrolysis ................................................................................................................................. 13799 3.2.3. Research and development of AEM water electrolysis ............................................................................................................... 13800 3.3. PEM water electrolysis .................................................................................................................................................................................... 13802 3.3.1. Working principle of pem water electrolysis ............................................................................................................................... 13803 ∗ Corresponding author at: Carbon Neutrality Demonstration and Research Center, Ulsan National Institute of Science and Technology, 50 UNIST-gil, Eonyang-up, Ulju-gun, Ulsan 44919, Republic of Korea. E-mail addresses: sampangishiva@gmail.com (S. Shiva Kumar), hklim@unist.ac.kr (H. Lim). https://doi.org/10.1016/j.egyr.2022.10.127 2352-4847/© 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).