Green Hydrogen Energy Systems explores the vital technologies and methods for generating, storing, and utilizing green hydrogen. By adopting an energy systems approach, the book offers a comprehensive review of green hydrogen systems, integrating principles, configurations, progress, and applications, bolstered by technoeconomic analyses and performance data. Addressing common challenges, it explains processes for developing and constructing basic and advanced green hydrogen systems. The book details the fundamentals of hydrogen technologies, including thermodynamics, kinetics, energy loss mechanisms, and costs. It covers aspects such as heat release, clean water usage in electrolyzers, system configurations, and includes real-world performance data, case studies, hydrogen hubs, safety, and economics. Presents a systems approach to hydrogen energy - Provides in-depth analysis of all key green hydrogen energy systems and related technologies, with all content supported by performance data - Offers technoeconomic analyses, design and operation modes, and integration mechanisms for green hydrogen energy systems Provides an energy systems approach to the principles, technologies, configurations, processes, and applications of green hydrogen energy systems Green Hydrogen Energy Systems delves into the most important green hydrogen generation, storage, and utilization methods and technologies. Taking an energy systems approach, the book provides a holistic review of green hydrogen energy systems, integrating the principles, configurations, progress, and applications, supported by technoeconomic analyses and performance data. The book addresses common challenges and explains the processes for developing and building basic and advanced green hydrogen energy systems, providing the necessary tools to analyze the processes involved, with a detailed discussion of all key technologies that are related to green hydrogen energy systems. The book provides a detailed description of the fundamentals of each hydrogen technology, including thermodynamics, kinetics, energy loss mechanisms, and cost. Also considered are aspects such as the release or use of heat, the need for clean water to use in water electrolyzers, and how these impact system configurations. Moreover, relevant system analysis tools and techniques are provided. Each process and model used in green hydrogen energy systems is explained in detail, along with relevant calculation methods, and supported by typical data deriving from these systems. An overview of active research projects, case studies, and manufacturers is also provided, which includes real-world performance data. Finally, the book offers dedicated chapters on hydrogen hubs and valleys, health and safety, and hydrogen economics. Written by an expert team working across complementary areas of hydrogen engineering, Green Hydrogen Energy Systems offers an invaluable resource to students, researchers, scientists, and professionals interested in understanding or developing hydrogen energy systems, and will be of interest to anyone involved in the hydrogen economy. Dr. Alexandros Arsalis is a Senior Researcher at the PHAETHON Centre of Excellence, University of Cyprus, where he leads the Green Hydrogen Energy Systems Group. He holds a Ph.D. in Mechanical Engineering from Aalborg University and an M.S. from Virginia Tech, both with a strong emphasis on hydrogen-based energy technologies. An internationally recognized expert in hydrogen systems, he has extensive experience in the design, modeling, optimization, and experimental validation of integrated green hydrogen solutions. His work focuses on system-level strategies that advance the transition toward resilient, low-carbon energy infrastructures. He has authored over 65 peer-reviewed publications and secured competitive fellowships and research grants from diverse funding programs. He has also played key roles in several international research consortia on hydrogen and sustainable energy, including Horizon Europe projects. Beyond his research, he is actively involved in education and training, having taught courses on renewable energy systems, numerical methods, and hydrogen technologies. In parallel, he contributes to capacity-building efforts through Erasmus+ projects on green hydrogen education across Europe and the Mediterranean. Additionally, he serves on editorial boards. Committed to science outreach, he actively promotes public engagement and knowledge transfer through various events, workshops, and training initiatives. Fanourios Kourougianni is a Researcher at the PHAETHON Centre of Excellence, University of Cyprus. He holds an M.Eng. in Mechanical Engineering from the National Technical University of Athens. His expertise lies in the advanced modeling and optimization of energy systems for the built environment. His current research focuses on the techno-economic assessment of green hydrogen technologies, with particular emphasis on their