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- Herausgeber: Wiley-VCH
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Provides a comprehensive guide to hydrogen technologies for sustainable energy production and practical deployment
With the growing urgency to reduce greenhouse gas emissions, decarbonize heavy industries, and diversify energy sources, hydrogen stands out as a versatile, clean energy carrier. Next-Generation Hydrogen Economy: Production, Storage, and Fuel Cell Technologies serves as an interdisciplinary roadmap for understanding and leveraging hydrogen’s vast potential. This timely volume meets the pressing need for a unified, research-informed resource that integrates hydrogen science, engineering, and policy—addressing both theoretical foundations and real-world implementation.
Written by experts in material science and energy research, Next-Generation Hydrogen Economy thoroughly examines hydrogen’s role in modern and future energy systems. The authors explore advanced production methods such as electrolysis, photocatalysis, and biological synthesis, while also detailing innovative storage technologies including metal hydrides, metal-organic frameworks (MOFs), and liquid organic hydrogen carriers (LOHCs). Practical chapters on hydrogen fuel cells highlight applications in transportation, grid storage, and heavy industry, with in-depth discussions on commercialization, economic feasibility, infrastructure challenges, and safety standards. Bridging research and practice, the book also delves into AI-driven catalyst development, smart hydrogen cities, and other emerging areas in the fields.
Equipping readers with the knowledge to drive innovation and make informed decisions in the rapidly evolving hydrogen economy, Next-Generation Hydrogen Economy:
- Integrates multidisciplinary insights from material science, electrochemistry, energy systems, and public policy
- Highlights novel hydrogen production techniques including photocatalysis and biological routes
- Analyzes the techno-economic challenges and opportunities of industrial-scale hydrogen deployment
- Features clear diagrams and process flowcharts to illustrate complex technical concepts and up-to-date case studies and global policy frameworks to contextualize hydrogen adoption
- Discusses safety standards, regulatory compliance, and risk mitigation strategies for hydrogen technologies
Emphasizing cross-sectoral integration of hydrogen, Next-Generation Hydrogen Economy: Production, Storage, and Fuel Cell Technologies is ideal for graduate and postgraduate students in courses such as Renewable Energy Systems, Energy Materials, and Sustainable Engineering within physics, chemistry, and energy engineering programs. It also serves as a valuable reference for professionals in electrochemistry, clean energy R&D, and energy policy analysis.
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Veröffentlichungsjahr: 2025
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Table of Contents
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
Acknowledgments
About the Authors
Disclosure of AI Use
Chapter 1: The Hydrogen Paradigm – Past, Present, and Future
1.1 Introduction to Hydrogen as an Energy Carrier
1.2 Evolution of Hydrogen as an Energy Carrier
1.3 Why Hydrogen? Comparison with Fossil Fuels and Renewables
1.4 Current Global Hydrogen Economy and Future Roadmaps
1.5 Key Challenges in Hydrogen Adoption and Infrastructure Development
References
Chapter 2: Innovative Hydrogen Production Technologies
2.1 Introduction to Hydrogen Production Technologies
2.2 Electrolysis: Advances in PEM, Alkaline, and Solid Oxide Electrolysis
2.3 Photocatalysis and Photoelectrochemical Water Splitting: Harnessing Solar Energy for Green Hydrogen
2.4 Thermochemical and Hybrid Processes: Sulfur-iodine Cycle, Metal Oxide Cycles
2.5 Biological Hydrogen Production: Algae, Bacteria, and Enzymatic Hydrogen Production
2.6 Comparative Analysis of Hydrogen Production Methods
2.7 Summary and Future Directions
References
Chapter 3: Advanced Materials for Hydrogen Production
3.1 Introduction to Advanced Materials for Hydrogen Production
3.2 High-performance Catalysts for Electrolysis
3.3 Nanomaterials and Composites for Enhanced Hydrogen Production
3.4 Durability and Degradation Challenges in Catalyst Materials
3.5 Cost-effective and Non-precious Metal Alternatives
3.6 Role of AI and Machine Learning in Material Discovery
3.7 Summary and Future Directions
References
Chapter 4: Hydrogen Storage – Challenges and Breakthroughs
4.1 Introduction to Hydrogen Storage
4.2 Physical Hydrogen Storage
4.3 Chemical Hydrogen Storage
4.4 Solid-state Hydrogen Storage
4.5 Safety Considerations and Risk Assessment in Hydrogen Storage
4.6 Future Directions in Hydrogen Storage
4.7 Summary and Future Perspectives
References
Chapter 5: Hydrogen Fuel Cells – Types and Mechanisms
5.1 Overview of Hydrogen Fuel Cells
5.2 Types of Hydrogen Fuel Cells
5.3 Mechanisms of Hydrogen Fuel Cells
5.4 Fuel Cell Components and Design
5.5 Fuel Cell Durability and Lifetime
5.6 Applications of Hydrogen Fuel Cells
5.7 Recent Advances and Research in Fuel Cell Technology
5.8 Environmental Impact and Sustainability of Hydrogen Fuel Cells
5.9 Challenges and Future Prospects
5.10 Conclusion
References
Chapter 6: Hydrogen-powered Transportation and Industrial Applications
6.1 Introduction
6.2 Hydrogen in Transportation Sector
6.3 Hydrogen Refueling Infrastructure: Current Progress and Challenges
6.4 Hydrogen in Industrial Applications
6.5 Key Technological and Economic Drivers for Hydrogen in Transportation and Industry
6.6 Environmental Impacts and Sustainability of Hydrogen in Transportation and Industry
6.7 Case Studies: Global Adoption of Hydrogen in Transportation and Industry
6.8 The Future Outlook for Hydrogen in Transportation and Industry
6.9 Conclusion
References
Chapter 7: Economics, Infrastructure, and Policy of Hydrogen Energy
7.1 Introduction
7.2 Economic Analysis of Hydrogen Production
7.3 Infrastructure Development and Logistics
7.4 Policy and Regulatory Frameworks
7.5 Investment and Financing Strategies
7.6 Emerging Hydrogen Economies: Growth in India, Australia, and South Korea
7.7 Challenges and Barriers to Hydrogen Commercialization
7.8 Case Studies: Leading Hydrogen Initiatives
7.9 The Future of Hydrogen Economics and Policy
7.10 Conclusion
References
Chapter 8: The Future of Hydrogen – Challenges, Innovations, and Sustainability
8.1 Introduction
8.2 AI and Data-driven Optimization in Hydrogen Research
8.3 Next-gen Hydrogen Technologies
8.4 Hydrogen’s Role in Achieving Net-zero Carbon Emissions
8.5 Hydrogen-powered Smart Cities and Off-grid Applications
8.6 Conclusion and Future Outlook
References
Chapter 9: Hydrogen Safety, Regulations, and Standardization
9.1 Introduction to Hydrogen Safety and Standardization
9.2 Hydrogen Safety Protocols in Production, Storage, and Transportation
9.3 Regulatory Landscape: International Hydrogen Safety Standards and Policies
9.4 Challenges in Standardization for Hydrogen Infrastructure
9.5 Hydrogen’s Role in Public Safety and Environmental Impact Assessment
9.6 Summary and Future Directions
References
Chapter 10: Industrial Scale-up and Commercialization of Hydrogen Technologies
10.1 Introduction to Industrial Hydrogen Scale Up
10.2 Challenges in Large-scale Hydrogen Production
10.3 Market Trends and Business Models for Hydrogen Commercialization
10.4 Case Studies of Successful Industrial Hydrogen Projects
10.5 Future Roadmap for Hydrogen Adoption
References
Index
End User License Agreement
List of Illustrations
Chapter 1
Figure 1.1 Hydrogen’s position in the periodic table and its key properties. Reproduced wit...
Figure 1.2 Timeline showing key milestones in hydrogen energy development.
Figure 1.3 Hydrogen’s role in the renewable energy ecosystem (integrating solar, wind, and...
Figure 1.4 Key challenges in hydrogen adoption and infrastructure development.
Chapter 2
Figure 2.1 A diagram illustrating the various hydrogen production methods, including fossil...
Figure 2.2 (a) Diagram of PEM processes – illustrating the working principle of PEM electro...
Figure 2.3 Mechanism of hydrogen production through sunlight using photocatalysis. This dia...
Figure 2.4 Redox mechanism for PEC water splitting. The diagram shows the redox processes a...
Figure 2.5 (a) FESEM images of materials used in the SI cycle, showing surface structure an...
Figure 2.6 (a) FESEM images of cerium oxide material used in metal oxide cycles, showing su...
Figure 2.7 (a) Algae-based hydrogen production pathways, including the role of photosynthes...
Chapter 3
Figure 3.1 Schematic representation of material applications in different hydrogen producti...
Figure 3.2 (a) Comparison of catalyst efficiency in HER and OER. (b) Schematic diagram of a...
Figure 3.3 (a) FESEM image of CNT. [36]/IOP Publishing/CC BY 3.0. (b) TEM image of CNT. Rep...
Figure 3.4 FESEM and TEM images of advanced composites for electrolysis and photocatalysis,...
Figure 3.5 Schematic representation of degradation mechanisms in hydrogen evolution catalys...
Chapter 4
Figure 4.1 Schematic representation of different hydrogen storage technologies. Reproduced ...
Figure 4.2 Schematic of compressed hydrogen storage tanks. Generated with AI using ChatGPT...
Figure 4.3 Schematic of cryogenic liquid storage tanks. Reproduced with permission from [46...
Figure 4.4 Hydrogen release from chemical hydrogen carriers. (a) Release of hydrogen from a...
Figure 4.5 (a) FESEM image of MOF-based hydrogen material. Reproduced with permission from...
Figure 4.6 Hydrogen storage safety mechanisms and risk mitigation strategies. [99]/MDPI/CC...
Chapter 5
Figure 5.1 Schematic representation of the basic operating mechanism of a hydrogen fuel cel...
Figure 5.2 Comparative overview of different types of hydrogen fuel cells in terms of opera...
Figure 5.3 Structure of a PEMFC. [33]/MDPI/CC BY 4.0.
Figure 5.4 Diagram illustrating the role of platinum-based catalysts in hydrogen oxidation...
Figure 5.5 Graphical comparison of operating temperature ranges and efficiency levels for c...
Figure 5.6 Exploded view of a fuel cell stack showing the MEA, bipolar plates, current coll...
Figure 5.7 Factors affecting fuel cell durability.
Chapter 6
Figure 6.1 Hydrogen applications across transportation modes. Reproduced with permission fr...
Figure 6.2 Working principle of hydrogen FCEV. Reproduced with permission from [24]/Elsevier.
Figure 6.3 Global development status of HRS, highlighting major deployment regions and infr...
Figure 6.4 Schematic of H
2
-DRI for green steel production. [57]/Springer Nature/CC BY 4.0.
Figure 6.5 Cement production with hydrogen integration. Process flow diagram of cement prod...
Chapter 7
Figure 7.1 Hydrogen production methods comparison. [10]/with permission of Elsevier.
Figure 7.2 Illustrates different hydrogen storage methods (compressed gas, liquid hydrogen,...
Figure 7.3 Infographic showcasing investment and policies from leading nations (EU, Japan,...
Chapter 8
Figure 8.1 Conceptual schematic of bio-inspired catalysts for hydrogen production. [46]/MDP...
Figure 8.2 Hydrogen’s contribution to net-zero carbons goals across industries. [61]/IEA/CC...
Chapter 9
Figure 9.1 Hydrogen safety challenges across the value chain – This figure illustrates crit...
Figure 9.2 Hydrogen storage safety mechanisms: This figure illustrates the key safety techn...
Figure 9.3 Standardization challenges in hydrogen refueling and storage infrastructure: Thi...
Chapter 10
Figure 10.1 Hydrogen’s role in industrial decarbonization across key sectors (steel, cement,...
Figure 10.2 Schematic of large-scale hydrogen production and distribution infrastructure. (P...
Figure 10.3 Hydrogen supply chain from production to end-user applications. [41]/MDPI/CC BY 4.0.
List of Tables
Chapter 1
Table 1.1 Comparison of hydrogen with other energy carriers (electricity, natural gas, gas...
Table 1.2 Evolution of hydrogen production methods with efficiency and cost trends.
Table 1.3 Comparison of hydrogen with other energy carriers (electricity, natural gas, gas...
Table 1.4 Comparison of hydrogen and battery energy storage systems in terms of storage du...
Table 1.5 Global hydrogen production by method (gray, blue, green hydrogen). (Placed at th...
Table 1.6 Comparison of hydrogen infrastructure costs vs. conventional energy infrastructure.
Chapter 2
Table 2.1 Benefits and limitations of alkaline electrolysis.
Table 2.2 Advantages and challenges of SOEC.
Table 2.3 Comparison of electrolysis technologies (PEM, alkaline, SOEC).
Table 2.4 Challenges in solar hydrogen production.
Table 2.5 Comparison of biological hydrogen production methods.
Table 2.6 Electrolysis vs. thermochemical hydrogen production.
Table 2.7 Comparative analysis of hydrogen production methods (cost, efficiency, scalabili...
Chapter 3
Table 3.1 Comparison of traditional and emerging catalysts for electrolysis.
Table 3.2 Comparison of catalyst degradation rates and stability enhancement strategies.
Table 3.3 Performance comparison of precious and non-precious metal catalysts.
Chapter 4
Table 4.1 Comparison of compressed gas and cryogenic liquid storage based on pressure, tem...
Table 4.2 Comparison of ammonia and LOHC-based hydrogen storage.
Table 4.3 Comparative safety assessment of compressed, cryogenic, and chemical hydrogen st...
Chapter 5
Table 5.1 A comparison of the efficiency, power density, and typical applications of vario...
Table 5.2 Factors affecting fuel cell durability.
Chapter 6
Table 6.1 Comparison of hydrogen FCVs vs. BEVs for heavy-duty transport.
Table 6.2 Key applications of hydrogen in the industrial sector.
Table 6.3 Environmental impact comparison of hydrogen vs. fossil fuels in industrial appli...
Chapter 7
Table 7.1 Comparative overview of hydrogen production methods.
Table 7.2 Global hydrogen market projections (2030–2050).
Table 7.3 Policy and regulatory support for hydrogen development in key regions.
Chapter 8
Table 8.1 Applications of AI in different hydrogen technologies.
Table 8.2 Comparison of quantum materials and bio-inspired catalysts in hydrogen applications.
Table 8.3 Hydrogen-powered smart cities and off-grid applications.
Chapter 9
Table 9.1 Comparative safety risks in different hydrogen production methods.
Table 9.2 Safety considerations for different hydrogen transportation methods.
Table 9.3 Comparison of hydrogen safety policies across major hydrogen economies.
Table 9.4 Key differences in hydrogen safety testing and certification across regions.
Chapter 10
Table 10.1 Cost comparison of different hydrogen production methods at an industrial scale.
Table 10.2 Global investment trends and hydrogen project financing models.
Guide
Cover
Table of Contents
Title Page
Copyright
Dedication
Preface
Acknowledgments
About the Authors
Disclosure of AI Use
Begin Reading
Index
End User License Agreement
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Next-Generation Hydrogen Economy
Production, Storage, and Fuel Cell Technologies
Dr. Peeyush Phogat
Dr. Shreya Sharma
Satyam Rawat
Authors
Dr. Peeyush Phogat
NIScPR
H.No-2176, Sector-13, HUDA
Bhiwani, Haryana
India
Dr. Shreya Sharma
NIScPR
H.No-696, Sector-23, HUDA
Bhiwani, Haryana
India
Satyam Rawat
Netaji Subhas University of Technology
Sec-3, Dwarka
New Delhi
India
Cover Design: Wiley
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Print ISBN: 9783527356010
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© 2026 WILEY-VCH GmbH, Boschstraße 12, 69469 Weinheim, Germany
All rights reserved (including those of translation into other languages, text and data mining and training of artificial technologies or similar technologies). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.
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ॐ नमः पार्वती पतये, हर-हर महादेव:
कर्मण्येवाधिकारस्ते मा फलेषु कदाचन।
मा कर्मफलहेतुर्भूर्मा ते सङ्गोऽस्त्वकर्मणि॥
To our beloved parents and loved ones – thank you for your unwavering support, encouragement, and the sacrifices you made that allowed us to pursue our passions. This work would not have been possible without your constant belief in us.
We also dedicate this book to all present and future seekers of knowledge, whose curiosity, perseverance, and spirit of discovery continue to shape a better world.
“The time will come when diligent research over long periods will bring to light things which now lie hidden. A single lifetime, even though entirely devoted to the sky, would not be enough for the investigation of so vast a subject … And so this knowledge will be unfolded only through long successive ages. There will come a time when our descendants will be amazed that we did not know things that are so plain to them … Many discoveries are reserved for ages still to come, when memory of us will have been effaced.”
— Seneca
May this book be a small contribution to the unfolding of that timeless journey.
Preface
The global energy landscape is undergoing a profound transformation as nations, industries, and societies confront the urgent challenges of climate change, fossil fuel depletion, and the pursuit of energy independence. In this context, hydrogen has emerged as a central pillar of the clean energy transition – promising a sustainable, versatile, and zero-emission alternative to conventional fuels across multiple sectors. From powering vehicles and storing renewable energy to decarbonizing hard-to-abate industries like steel, cement, and ammonia production, hydrogen technologies are paving the way toward a carbon-neutral future.
This book, Next-Generation Hydrogen Economy: Production, Storage, and Fuel Cell Technologies, is designed to serve as a comprehensive guide for academics, industry professionals, policymakers, and students who are actively engaged in or entering the hydrogen energy field. It brings together a detailed exploration of hydrogen’s scientific foundations, technological innovations, infrastructure development, and future opportunities. Drawing on the latest research and real-world case studies, this book provides a clear and practical understanding of the key components necessary to scale-up and commercialize hydrogen systems globally.
The content spans 10 chapters, beginning with the historical evolution and current status of the hydrogen economy, followed by in-depth analyses of advanced production techniques, material innovations, storage strategies, and fuel cell mechanisms. The latter half of the book focuses on transportation and industrial applications, policy and economic frameworks, safety standards, and the challenges of industrial scale-up. Importantly, it also looks ahead to the future – exploring AI-driven research, smart hydrogen cities, and the role of hydrogen in achieving net-zero carbon targets.
Our motivation in writing this book stems from the need for an interdisciplinary resource that bridges chemistry, physics, materials science, engineering, and energy policy. The hydrogen transition is not only a technological endeavor but a societal one, requiring global cooperation and informed decision-making. We hope this book contributes to that mission by equipping readers with the knowledge needed to innovate, collaborate, and lead in the hydrogen era.
We express our gratitude to the researchers, engineers, institutions, and organizations whose work continues to push the boundaries of hydrogen technology. We also thank the publishing team and reviewers whose insights helped refine and shape this book.
We invite you, the reader, to explore the fascinating journey of hydrogen – one molecule with the power to fuel a more sustainable world.
Dr. Peeyush Phogat
Dr. Shreya Sharma
Mr. Satyam Rawat
Acknowledgments
We extend our heartfelt gratitude to Prof. Ranjana Jha, Vice Chancellor, Indira Gandhi Delhi Technical University for Women, for her inspiring leadership, guidance, and continued encouragement throughout our academic journey. We are deeply thankful to Prof. Sukhvir Singh and Prof. Nandlal of the Delhi Skill and Entrepreneurship University for their invaluable insights, mentorship, and unwavering support at every step of this endeavor.
Our sincere appreciation goes to the Wiley publishing team for recognizing the value of this work and providing us with the opportunity to share our vision with the global research community. Your professionalism and support have made this project a reality.
We also thank our research team, whose dedication, resilience, and collaborative spirit have been a constant source of strength and motivation. Your contributions, both seen and unseen, have helped shape the foundation of this book.
Lastly, to our families and loved ones – thank you for your endless patience, sacrifices, and unconditional love. This work is a reflection of all the support you have given us.
—Dr. Peeyush Phogat, Dr. Shreya Sharma, and Mr. Satyam Rawat
About the Authors
Dr. Peeyush Phogat completed his PhD in the Department of Physics at Netaji Subhas University of Technology. His research emphasizes the synthesis and characterization of advanced materials for energy applications, focusing on innovations in energy storage, photodetection, and sustainability. A prolific researcher, Peeyush has authored 36 research papers in reputed journals, contributing to advancements in electrochemical applications and renewable energy materials. He has also published many review articles providing in-depth insights into emerging trends in material science and energy technologies. In addition, Peeyush has contributed 18 book chapters across diverse domains in material science and co-authored three books: Next-Generation Electrochemical Devices: From Principles to Applications, The Future of Energy: How Innovative Devices Shape Our Environment, and AI-Driven Innovations in Electrochemical Technologies for Sustainable Energy Solutions. Driven by a commitment to scientific progress, Peeyush aims to advance sustainable energy solutions through material science innovations and interdisciplinary research.
Dr. Shreya Sharma is a physicist who earned her PhD in Physics from Netaji Subhas University of Technology, where her research was centered on the exploration of exceptional properties exhibited by nanomaterials and their potential contributions to advancing renewable energy technologies. Her primary focus lies in investigating the unique properties of two-dimensional (2D) materials and their electrochemical study, specifically transition metal dichalcogenides, with the aim of applying these findings to enhance solar cells, supercapacitors, photodetectors, hydrogen production, and electrochemical sensing. Her dedication to leveraging advanced materials for sustainable energy solutions reflects her vision of contributing to societal progress through innovative technology. Currently, she is working to identify sustainable energy resources, with a specific focus on blue energy foresight. She is also the author and co-editor of six scientific books and more than 40 research papers in esteemed journals. Driven by a deep commitment to environmental sustainability, Dr. Sharma’s work embodies her passion for scientific advancement in service to future energy needs.
Mr. Satyam Rawat is currently pursuing an MSc in Physics, specializing in the synthesis and characterization of 2D materials like reduced graphene oxide. His research focuses on developing nanocomposites of these materials for advanced applications, including supercapacitors and photodetectors. His work aims to enhance the performance and versatility of energy storage and optoelectronic devices through innovative material design and optimization.
Disclosure of AI Use
In accordance with publishing guidelines and ethical authorship practices, the authors of this book affirm the following regarding the use of artificial intelligence (AI) tools in the preparation of this manuscript:
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.
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Chapter 1The Hydrogen Paradigm – Past, Present, and Future
1.1 Introduction to Hydrogen as an Energy Carrier
1.1.1 Definition and Fundamental Properties of Hydrogen
Hydrogen, the lightest and most abundant element in the universe, plays a crucial role in both natural and engineered energy systems. It is represented by the chemical symbol H and has an atomic number of 1, meaning it contains only one proton in its nucleus. As a fundamental building block of the universe, hydrogen is a primary component of stars and gas giants and is widely found in water, hydrocarbons, and biological systems. Its significance in energy applications arises from its high-energy density and clean combustion properties, making it an ideal candidate for sustainable fuel alternatives [1].
The atomic structure of hydrogen is the simplest among all elements, consisting of a single proton and an electron. However, hydrogen exhibits multiple isotopic forms, which are distinguished by the number of neutrons in the nucleus. The three naturally occurring isotopes of hydrogen are:
Protium (^1H)
– The most abundant isotope, accounting for over 99.98% of naturally occurring hydrogen. It consists of a single proton and no neutrons.
Deuterium (^2H or D)
– This isotope contains one proton and one neutron, making it twice as heavy as protium. Deuterium is stable and occurs naturally in small quantities (about 0.015% of Earth’s hydrogen). It is commonly used in nuclear fusion research and heavy water applications in nuclear reactors.
Tritium (^3H or T)
– A radioactive isotope containing one proton and two neutrons. Tritium has a half-life of 12.3 years and is primarily produced in nuclear reactions. It is used in specialized applications such as nuclear fusion research and self-luminous materials.
Hydrogen’s placement in the periodic table highlights its unique properties and chemical versatility (as illustrated in Figure 1.1). Despite being positioned in Group 1 due to its single valence electron, hydrogen exhibits behavior distinct from alkali metals, and in some respects, resembles halogens. It readily forms bonds with other elements, contributing to a vast range of compounds, including water (H2O), hydrocarbons (CH4, C2H6), and acids (HCl, H2SO4) [2].
Figure 1.1 Hydrogen’s position in the periodic table and its key properties. Reproduced with permission of [5]/John Wiley & Sons.
The properties of hydrogen that make it particularly attractive as an energy carrier are its lightweight nature, high-energy content, and environmental benefits [3]. Some key physical and chemical characteristics of hydrogen relevant to energy applications are as follows:
Low Atomic and Molecular Mass
– Hydrogen is the lightest element, with an atomic mass of 1.008 u. Molecular hydrogen (H
2
) has a molecular weight of 2.016 g/mol, making it significantly lighter than other fuels. Its low density (0.0899 g/L at standard conditions) presents challenges for storage and transportation, necessitating advanced containment techniques such as compression, liquefaction, or chemical storage. These storage challenges are particularly important in applications where large quantities of hydrogen need to be transported or stored over extended periods.
High-Energy Density
– Despite its low volumetric density, hydrogen has an exceptionally high gravimetric energy density of 120 MJ/kg, nearly three times that of gasoline (44 MJ/kg). This property makes hydrogen a promising alternative for applications requiring lightweight, high-energy fuels, such as aerospace, fuel cell vehicles, and portable power systems. Its high-energy density per unit mass also positions hydrogen as an ideal candidate for energy applications in sectors that demand significant power with minimal weight, such as aviation and heavy-duty transport.
Chemical Reactivity and Combustion
– Hydrogen exhibits strong reducing properties, allowing it to participate in various chemical reactions, including redox processes and catalysis. When burned in the presence of oxygen, hydrogen reacts exothermically:
This reaction releases a significant amount of energy and produces only water vapor as a byproduct, making hydrogen a zero-emission fuel when used in combustion engines or fuel cells (as illustrated in Figure 1.1). The clean nature of hydrogen combustion positions it as an attractive alternative to fossil fuels, which emit harmful greenhouse gases and pollutants.
Flammability and Explosion Limits
– Hydrogen has a wide flammability range (4–75% in air) and a low ignition energy, making it highly reactive. This characteristic necessitates strict safety measures in hydrogen storage and handling. However, due to its low molecular weight, hydrogen dissipates quickly in the atmosphere, reducing the risk of prolonged exposure to explosive concentrations. These safety considerations are essential in ensuring the safe adoption of hydrogen in various energy systems.
Electrochemical Potential in Fuel Cells
– Hydrogen’s ability to release electrons in an electrochemical reaction makes it an ideal fuel for proton exchange membrane (PEM) fuel cells, where hydrogen is split into protons and electrons to generate electricity. This application is central to hydrogen-powered vehicles, backup power systems, and stationary fuel cell applications. The efficiency of hydrogen fuel cells, combined with their zero-emission nature, offers a promising solution for a wide range of applications, from transportation to stationary power generation.
Interaction with Metals and Storage Challenges
– Hydrogen can diffuse through metals, leading to hydrogen embrittlement, which weakens structural materials over time. This property impacts pipeline transport and metal storage solutions, requiring specialized materials to contain hydrogen safely. Engineers are working to develop advanced materials that can withstand the effects of hydrogen embrittlement, ensuring the safe transport and storage of hydrogen.
Cryogenic Liquefaction
– Hydrogen has a boiling point of −252.87 °C, necessitating cryogenic technology for liquid hydrogen storage. Liquefied hydrogen (LH
2
) is often used in rocket propulsion and energy storage applications where high-density storage is required. The cryogenic liquefaction of hydrogen enables its storage in compact, dense forms, making it suitable for high-energy applications such as space exploration.
Hydrogen’s distinct physical and chemical properties underscore its potential as a clean and sustainable energy source, while also presenting technical challenges that require innovative solutions for widespread adoption. As the world shifts toward decarbonization and renewable energy integration, hydrogen will continue to play a pivotal role in shaping the future energy landscape [4].
1.1.2 Why Hydrogen Is Considered a Clean Energy Carrier
Hydrogen has gained global recognition as a clean energy carrier due to its potential to provide a sustainable, zero-emission alternative to conventional fossil fuels. Its unique properties, including high-energy density, efficiency in energy conversion, and versatility across multiple sectors, make it a promising candidate for the future of energy. Hydrogen can be used in fuel cells, internal combustion engines, and industrial applications while producing minimal environmental impact. The key reasons hydrogen is considered a clean energy carrier include its zero-emission potential, high efficiency in energy conversion, and favorable comparison with fossil fuels and renewables [6].
One of the most compelling advantages of hydrogen as an energy carrier is its zero-emission potential when combusted or used in fuel cells. Unlike fossil fuels, which release carbon dioxide (CO2), nitrogen oxides (NOx), sulfur oxides (SOx), and particulate matter, hydrogen produces only water vapor (H2O) when reacted with oxygen. This clean combustion process is represented by the reaction (1.1). This reaction is highly exothermic, releasing a significant amount of energy while generating no carbon-based emissions. Due to this characteristic, hydrogen is considered a viable alternative to coal, oil, and natural gas in sectors where emissions are a major concern, such as transportation, power generation, and heavy industry. Additionally, hydrogen can be produced from renewable energy sources, such as solar, wind, and hydropower, through electrolysis, making it a truly sustainable energy carrier. Green hydrogen, produced via water electrolysis powered by renewables, has a net-zero carbon footprint, making it an ideal candidate for long-term energy storage and grid stabilization [7].
Hydrogen can also be blended with natural gas in existing pipeline infrastructure to reduce carbon emissions in heating applications. A blend of 20% hydrogen with natural gas can lower overall emissions without requiring major modifications to current gas infrastructure. In contrast, using pure hydrogen in fuel cells ensures completely carbon-free power generation, making it particularly suitable for electric vehicles, stationary power systems, and portable energy applications [8].
Hydrogen’s efficiency in energy conversion is another reason for its growing popularity as a clean energy carrier. When used in fuel cells, hydrogen undergoes an electrochemical reaction rather than combustion, significantly improving efficiency and reducing energy losses. Fuel cells can achieve an efficiency of 50–60%, much higher than internal combustion engines, which typically operate at 20–30% efficiency due to heat losses. When combined with waste heat recovery systems, fuel cells can reach an overall efficiency of 80–90%, making them one of the most efficient energy conversion technologies available. In contrast, traditional coal-fired power plants have efficiencies of only 35–40%, with the remainder of the energy lost as heat. The sustainability of hydrogen is further enhanced by its ability to be produced domestically using locally available resources. Unlike fossil fuels, which are finite and concentrated in specific regions, hydrogen can be derived from water (H2O), biomass, or industrial byproducts. This enhances energy security by reducing dependence on oil and gas imports, creating a more resilient and distributed energy system. Furthermore, hydrogen can act as an energy storage medium for intermittent renewables like solar and wind. Surplus electricity generated during high renewable output periods can be used to produce hydrogen via electrolysis, which can then be stored and converted back to electricity when demand is high (as depicted in Table 1.1). This capability makes hydrogen a key enabler of grid stability and energy balancing, addressing one of the major challenges of renewable energy integration [9].
A comprehensive comparison of hydrogen with other energy carriers, including electricity, natural gas, and gasoline, reveals its potential advantages in energy density, emissions, and efficiency (as shown in Table 1.1). Hydrogen has a higher energy content per unit mass (120 MJ/kg) than gasoline (44 MJ/kg) and natural gas (53 MJ/kg). This makes hydrogen particularly attractive for aerospace and heavy-duty transport, where weight considerations are critical. However, hydrogen’s low volumetric energy density presents storage and transportation challenges, requiring compression, liquefaction, or solid-state storage solutions [10].
Table 1.1 Comparison of hydrogen with other energy carriers (electricity, natural gas, gasoline) in terms of energy density, emissions, and efficiency. (Placed at the end of this section to highlight advantages and limitations.)
Energy carrier
Gravimetric energy density (MJ/kg)
Emissions (CO
2
per MJ energy)
Efficiency (%)
Storage challenges
Hydrogen (H
2
)
120
0 (Fuel cells)
50–60 (Fuel cells)
Requires compression/liquefaction [
12
]
Gasoline
44
73 g CO
2
/MJ
20–30 (ICEs)
Liquid fuel, stable storage [
13
]
Natural gas (CH
4
)
53
50 g CO
2
/MJ
30–40 (Gas turbines)
Requires pipelines or liquefied natural gas (LNG) storage [
14
]
Electricity (battery storage)
0.3 (Li-ion)
Depends on grid mix
85–90 (BEVs)
Limited by battery capacity and lifespan [
15
]
Emissions Profile:
Hydrogen emits zero greenhouse gases when used in fuel cells.
Natural gas, while cleaner than coal, still emits 50–60% of the CO
2
per unit energy compared to gasoline.
Gasoline and diesel combustion produce CO
2
, NO
x
, SO
x
, and particulate matter, contributing to air pollution and climate change.
Efficiency:
Hydrogen fuel cells operate at 50–60% efficiency and can reach 80–90% with heat recovery.
Internal combustion engines (ICEs) powered by gasoline or diesel typically have efficiencies of 20–30%, with significant losses due to heat dissipation.
Battery electric vehicles (BEVs) achieve efficiencies of 85–90%, but their energy storage capacity is limited compared to hydrogen fuel cells.
Hydrogen, with its zero-emission potential, efficiency in energy conversion, and favorable emissions profile, stands out as a clean energy carrier capable of playing a pivotal role in the global transition toward a more sustainable and decarbonized energy future [11].
Hydrogen stands out as a clean, efficient, and sustainable energy carrier with the potential to replace fossil fuels in multiple sectors. Its zero-emission nature, high-energy conversion efficiency, and ability to store and transport renewable energy make it a key enabler of the global energy transition. While challenges such as storage, infrastructure, and cost remain, ongoing advancements in hydrogen production, distribution, and utilization will drive its widespread adoption. As global policies shift toward carbon neutrality, hydrogen is poised to play a pivotal role in achieving sustainable and emission-free energy systems [16].
1.1.3 Role of Hydrogen in Decarbonization Efforts
The transition to a low-carbon economy is crucial for mitigating climate change, and hydrogen has emerged as a key enabler of global decarbonization efforts. As a clean and versatile energy carrier, hydrogen can significantly reduce greenhouse gas (GHG) emissions by replacing fossil fuels in transportation, industry, and power generation. Moreover, its ability to integrate with renewable energy sources makes it an essential component of a sustainable energy system. By leveraging green hydrogen production, advancements in fuel cell technology, and hydrogen infrastructure development, the world can accelerate toward carbon neutrality and meet climate goals set by international agreements such as the Paris Agreement [17].
Carbon neutrality – achieving net-zero carbon dioxide (CO2) emissions – requires a fundamental shift away from fossil fuels toward clean energy solutions. Hydrogen offers a zero-emission alternative when produced using renewable energy sources such as solar and wind power. Unlike coal, oil, and natural gas, which emit CO2, methane (CH4), and other pollutants, hydrogen can be used in fuel cells and combustion processes while producing only water (H2O) as a byproduct. To achieve deep decarbonization, hydrogen must be produced, stored, and utilized in a way that minimizes emissions. This includes transitioning from gray hydrogen (derived from fossil fuels) to blue hydrogen (produced with carbon capture and storage) and ultimately to green hydrogen (generated via electrolysis powered by renewables). Large-scale deployment of green hydrogen is expected to reduce CO2 emissions in hard-to-abate sectors and contribute significantly to global carbon neutrality goals [18].
Sectors Benefiting from Hydrogen-Based Decarbonization
Transportation:
The transportation sector is one of the largest contributors to global CO
2
emissions, primarily due to the reliance on gasoline and diesel-powered vehicles. Hydrogen-based solutions, such as fuel cell electric vehicles (FCEVs), offer a zero-emission alternative to ICEs. Unlike BEVs, which require long charging times, FCEVs can be refueled quickly and have longer driving ranges, making them ideal for heavy-duty transport, buses, trains, and maritime shipping. Hydrogen-powered aviation is also under development, with companies exploring liquid hydrogen fuel for long-haul flights [
19
].
Industry:
Heavy industries, such as steel, cement, and chemical manufacturing, account for a significant share of global carbon emissions. These industries rely on high-temperature processes that are difficult to electrify. Hydrogen, especially in the form of green hydrogen, can serve as a clean alternative to coal and natural gas in steel production (via hydrogen direct reduction), ammonia synthesis, and chemical refining. By replacing fossil-based hydrogen (gray hydrogen) with green hydrogen, industries can achieve substantial CO
2
emission reductions while maintaining efficiency [
20
].
Power Generation:
Hydrogen can play a vital role in stabilizing electricity grids and supporting renewable energy expansion. While solar and wind energy are crucial for decarbonization, their intermittent nature presents challenges for grid stability. Hydrogen can be used to store excess renewable energy during periods of low demand and later converted back to electricity via fuel cells or hydrogen turbines when needed. This ability to act as a long-term energy storage solution makes hydrogen an essential component of future power systems. Countries are already testing hydrogen-fired gas turbines to replace traditional natural gas power plants, further reducing carbon emissions from the power sector [
21
].
Hydrogen’s compatibility with renewable energy is a major advantage in global decarbonization efforts. When solar and wind farms generate excess power, this surplus energy can be used for water electrolysis, producing green hydrogen. This hydrogen can then be stored and transported to be used in fuel cells, industrial applications, or power plants. The concept of “power-to-gas” (P2G) allows renewable energy to be converted into hydrogen, effectively addressing energy storage and grid-balancing challenges. Furthermore, hydrogen pipelines can integrate with existing gas networks, allowing for blending hydrogen with natural gas to progressively reduce carbon footprints. Some countries are already experimenting with 20–30% hydrogen blending, with the goal of transitioning to 100% hydrogen-based heating and electricity generation [22].
Hydrogen is a critical enabler of global decarbonization efforts, offering solutions for carbon neutrality in transportation, industry, and power generation. By leveraging green hydrogen production and integrating it with renewable energy systems, nations can significantly reduce GHG emissions, enhance energy security, and create a sustainable energy future. While challenges remain, including infrastructure development and production costs, ongoing technological advancements and policy support will accelerate the global hydrogen economy, making it a cornerstone of climate change mitigation strategies [23].
1.2 Evolution of Hydrogen as an Energy Carrier
1.2.1 Early Uses of Hydrogen
Hydrogen has a long history of use, beginning with its discovery in the eighteenth century and gradually expanding into various industrial and scientific applications. The first documented production of hydrogen dates back to 1671, when the English scientist Robert Boyle observed the gas while experimenting with metals and acids. However, it was not until 1766 that the British chemist Henry Cavendish identified hydrogen as a distinct element, isolating it and recognizing its flammability. His experiments revealed that hydrogen, when burned, produced water, a crucial discovery that laid the foundation for understanding its chemical properties [24].
One of the earliest and most iconic applications of hydrogen was in balloons. In the late eighteenth and early nineteenth centuries, hydrogen gas became widely used to fill balloons, offering a practical means of achieving flight due to its low molecular weight and high buoyancy. The French brothers Joseph-Michel and Jacques-Étienne Montgolfier are often credited with the development of the first hot air balloons, but hydrogen’s ability to lift heavier loads made it an attractive alternative. In 1783, the first hydrogen-filled balloon flight took place, and soon after, hydrogen was used for a series of daring aerial adventures. It was particularly instrumental in early ballooning expeditions, including those by famous figures such as Jean-Pierre Blanchard and Henry Coxwell. Despite its potential for flight, the flammability of hydrogen eventually led to its replacement by safer, less volatile gases like helium. Beyond ballooning, hydrogen found early use in various industrial processes. In the nineteenth century, it became an essential component in the production of ammonia through the Haber process, a critical advancement for fertilizer production that revolutionized agriculture. Hydrogen’s role in hydrogenation processes also began to take shape during this period, facilitating the conversion of unsaturated fats and oils into solid forms, such as margarine. This process, known as catalytic hydrogenation, is still widely used in the food industry today. Overall, the early use of hydrogen paved the way for its later applications in energy and chemical processes. Its discovery and the subsequent exploration of its potential led to significant technological and industrial developments, establishing hydrogen as a key element in the scientific and industrial revolutions of the eighteenth and nineteenth centuries [25].
1.2.2 Development of Hydrogen Production Technologies
The development of hydrogen production technologies has evolved significantly from early methods like electrolysis to the sophisticated reforming processes used today. Hydrogen’s potential as an energy carrier has driven scientists and engineers to explore various methods for its generation, resulting in numerous breakthroughs over the centuries. In the late eighteenth century, the first recorded instance of hydrogen production occurred via electrolysis, a process that remains relevant to this day. In 1800, William Nicholson and Anthony Carlisle demonstrated the electrolysis of water, breaking it down into hydrogen and oxygen using an electric current. This was the first time hydrogen had been intentionally produced from water, marking a major milestone in hydrogen energy development. Electrolysis became a foundational technology for hydrogen production, as it provided a means of generating hydrogen from abundant and renewable water sources [26].
The next significant breakthrough came in the nineteenth century, with the development of steam reforming, which remains one of the most widely used methods for hydrogen production today. In the early 1800s, chemists discovered that high temperatures and the presence of a catalyst could be used to extract hydrogen from hydrocarbons, such as methane. Steam reforming, which involves reacting methane with steam at high temperatures (700–1,000 °C) to produce hydrogen, carbon monoxide, and a small amount of carbon dioxide, became a major industrial method. This process, still widely used in refineries and chemical plants, is efficient but produces carbon-based byproducts, making it a less environmentally friendly option compared to newer technologies like water electrolysis powered by renewable energy sources [27]. In the mid-twentieth century, advances in hydrogen production continued with the introduction of more efficient methods, including partial oxidation and auto-thermal reforming. These processes combined steam reforming with other chemical reactions to increase hydrogen yield and reduce energy consumption. Additionally, during this time, the industrial-scale production of hydrogen saw rapid growth, especially with its increasing use in the petroleum industry and for the production of ammonia [28]. The late twentieth and early twenty-first centuries saw a surge in research aimed at improving the sustainability of hydrogen production. The introduction of “green hydrogen” production methods, particularly through electrolysis powered by renewable energy sources such as wind, solar, and hydropower, represented a breakthrough in decarbonizing hydrogen production. These methods have gained momentum in recent years, driven by the need for cleaner energy alternatives to fossil fuels. Green hydrogen is produced by splitting water molecules into hydrogen and oxygen using electricity derived from renewable sources, resulting in a zero-emission production process that holds great promise for reducing global carbon footprints [29].
Alongside green hydrogen, developments in biomass gasification, which uses organic materials to produce hydrogen, have also emerged as another potential source of hydrogen. This method converts biomass into hydrogen-rich gases, making it an attractive option for regions with abundant agricultural or forest waste. As shown in Figure 1.2, the timeline of hydrogen energy development highlights the key milestones in hydrogen production, from the early electrolysis experiments to the modern reforming processes and the ongoing push for sustainable hydrogen generation technologies. This progression reflects the growing understanding of hydrogen’s potential as a clean energy carrier and the increasing demand for efficient, environmentally friendly hydrogen production methods to meet the energy needs of the future. The future of hydrogen production lies in further innovations, such as advanced electrolyzers and more cost-effective renewable energy integration, ensuring its role in the global transition to a cleaner energy system [30, 31].
Figure 1.2 Timeline showing key milestones in hydrogen energy development.
1.2.3 The Rise of Fuel Cells and Space Applications
The rise of hydrogen fuel cells in space applications marked a significant turning point in both the development of fuel cell technology and the broader use of hydrogen as an energy carrier. In the mid-twentieth century, NASA’s space programs became one of the most prominent arenas for demonstrating the potential of hydrogen fuel cells, a technology that would later find its way into various commercial applications. The development of hydrogen fuel cells for space missions began in the 1950s, with the realization that traditional power sources would not meet the unique needs of space exploration. Fuel cells, which generate electricity through the electrochemical reaction between hydrogen and oxygen, provided a lightweight, reliable, and long-lasting energy source. This made them ideal for powering spacecraft, where weight and efficiency are critical. NASA’s interest in fuel cells led to significant advancements in both the technology and its application in space missions [32, 33].
In the early 1960s, NASA began using hydrogen fuel cells for its Gemini and Apollo space programs. The Apollo spacecraft, which carried astronauts to the Moon, relied on fuel cells to generate electricity and supply potable water for the astronauts. The fuel cell system was highly efficient, producing both electricity and water as a byproduct, which was particularly important in the confined environment of the spacecraft. The Apollo missions demonstrated that hydrogen fuel cells could operate efficiently in space, providing a continuous power source for critical systems while also producing water for consumption by the astronauts. The success of hydrogen fuel cells in the Apollo missions catalyzed their further development and adoption [34]. By the 1970s, fuel cells were widely used in space exploration, and NASA’s space shuttle program relied heavily on hydrogen fuel cells for power. The space shuttle, which launched in 1981, was equipped with fuel cells that generated electricity from hydrogen and oxygen during flight. These fuel cells provided electrical power for the shuttle’s systems and were essential for supporting the crew’s needs during both launch and re-entry. The use of hydrogen fuel cells in space applications was a testament to their reliability, long life, and efficiency under extreme conditions. Parallel to NASA’s work in space, hydrogen fuel cells began to receive commercial attention. In the 1960s and 1970s, several early experiments were conducted in the automotive and industrial sectors, where fuel cells were tested for use in vehicles and backup power systems. Although the technology faced challenges in terms of cost and scalability, it laid the groundwork for future developments. In the 1990s, commercial interest in fuel cells increased as the need for clean, efficient energy sources grew, particularly in the context of environmental concerns and the development of alternative energy solutions [35].
The early experiments and commercial developments of hydrogen fuel cells, although limited in scope at the time, demonstrated their potential to provide clean energy for various applications. Today, hydrogen fuel cells have moved from the realm of space exploration to terrestrial applications, including transportation, stationary power systems, and backup generators. The development of fuel cells for NASA’s space programs played a pivotal role in proving the viability of hydrogen as an energy carrier, and it continues to be a driving force in the development of fuel cell technologies today. As the world moves toward cleaner, more sustainable energy solutions, hydrogen fuel cells are positioned to play a key role in decarbonizing sectors such as transportation and power generation, building upon the legacy of their success in space applications [36, 37].
1.2.4 Hydrogen’s Transition to an Energy Vector in the Twenty-first Century
Hydrogen has undergone a remarkable transformation over the last few decades, evolving from a simple industrial gas to a cornerstone of clean energy solutions in the twenty-first century. Historically, hydrogen was primarily used in industries such as refining, ammonia production, and chemical synthesis. It was seen as a useful but niche industrial product, and its applications were largely confined to these sectors. However, as the world faces mounting challenges associated with climate change, air pollution, and the depletion of fossil fuels, hydrogen’s potential as a clean energy carrier has gained global attention, setting the stage for its significant role in the future energy landscape. The shift of hydrogen from an industrial gas to a clean energy solution is largely driven by the increasing demand for decarbonization in various sectors, particularly in transportation, power generation, and heavy industry. One of the most compelling aspects of hydrogen is its versatility: it can be used in fuel cells for vehicles, stored as an energy carrier, and even integrated into industrial processes to replace carbon-intensive fuels. As concerns about GHG emissions have intensified, hydrogen has emerged as a key solution to reduce emissions in hard-to-abate sectors like steel production and long-distance transportation [38].
In the early twenty-first century, hydrogen began to be seen not just as a chemical feedstock but as a vector for storing and transporting renewable energy. The rise of renewable energy sources, such as solar and wind, has posed significant challenges to grid stability due to their intermittent nature. Hydrogen offers a solution to this challenge by acting as an energy carrier. Surplus renewable energy can be used to produce hydrogen through electrolysis, and this hydrogen can then be stored for use when renewable energy generation is low. This ability to store and transport energy over long distances makes hydrogen a critical player in the transition to a low-carbon energy system [39].
The global policy landscape has also shifted significantly to support hydrogen adoption. Countries around the world are recognizing hydrogen as an essential part of their energy transition strategies. In Europe, for example, the EU has set ambitious goals for hydrogen development, focusing on the production of green hydrogen and its integration into the energy grid. The EU Hydrogen Strategy, unveiled in 2020, aims to scale up the production of renewable hydrogen, with a target of producing 10 million tons of green hydrogen annually by 2030 [40]. In Japan, hydrogen has been central to the country’s energy strategy, with policies supporting hydrogen fuel cell vehicles, infrastructure development, and international hydrogen trade. The Japanese government’s commitment to hydrogen is exemplified by the country’s early leadership in hydrogen fuel cell vehicles and its establishment of a national hydrogen roadmap [41]. Similarly, governments in South Korea, China, and the United States have been prioritizing hydrogen in their energy policies. South Korea has launched a hydrogen roadmap aimed at boosting hydrogen production and adoption in various sectors, including transportation, while China’s commitment to hydrogen has been reinforced by large-scale pilot projects and funding for hydrogen infrastructure. In the United States, hydrogen is increasingly seen as a key component of decarbonizing the industrial sector, with both state and federal initiatives focused on developing hydrogen technologies and expanding infrastructure [42].
At the same time, there has been an explosion of research and development in hydrogen production technologies. Early methods of hydrogen production, such as steam methane reforming (SMR) and electrolysis, have been refined to improve efficiency and reduce costs. SMR, which remains the most common method of hydrogen production, has been traditionally criticized for its high carbon emissions [43]. However, with advancements in carbon capture and storage (CCS) technologies [44], low-carbon versions of SMR are now being explored. Meanwhile, electrolysis, which splits water into hydrogen and oxygen using electricity, is gaining momentum, particularly when powered by renewable sources of energy. Innovations in electrolyzer technologies are rapidly increasing the efficiency of electrolysis, driving down costs and making green hydrogen more competitive in the market. The continuous evolution of hydrogen production methods is depicted in Table 1.2, which shows key milestones in hydrogen generation technologies, along with trends in efficiency and cost. The table highlights the progression from early industrial hydrogen production methods to modern techniques, such as green hydrogen production via electrolysis, and illustrates the declining costs and increasing efficiencies over time. As these technologies mature and scale, hydrogen is becoming an increasingly viable option for large-scale, clean energy systems.
Table 1.2 Evolution of hydrogen production methods with efficiency and cost trends.
Hydrogen production method
Description
Efficiency (%)
Cost trends (per kg)
Key milestones
Electrolysis (early methods)
Electrolysis of water using direct current (DC)
~50–60
High ($10–$12)
Early nineteenth century: discovery and initial use [
45
]
SMR
Hydrogen produced by reacting natural gas with steam
~65–75
$1–$3
Industrial scale-up in the twentieth century [
46
]
Coal gasification
Hydrogen produced from coal through a gasification process.
~65–70
$1.5–$4
Twentieth century: used for industrial purposes [
47
]
Electrolysis (modern)
Modern electrolyzers powered by renewable electricity
70–85
~$3–$6
Twenty-first century: adoption of green hydrogen [
48
]
Biomass gasification
Hydrogen produced from organic materials (e.g., biomass)
~60–70
~$2–$6
Increasing interest with bioenergy [
49
]
Blue hydrogen (SMR + CCS)
SMR with CCS to reduce emissions
~75–80
~$2–$4
2020s: focus on decarbonizing hydrogen [
50
]
Green hydrogen (electrolysis)
Electrolysis powered by renewable sources (solar, wind, etc.)
70–85
~$3–$6
2020s: scaling up with renewable energy [
51
]
As hydrogen becomes more integrated into the global energy landscape, the role it plays in decarbonization efforts is expected to expand dramatically. The shift from industrial gas to clean energy vector is already underway, with research, innovation, and policy support driving hydrogen’s role in addressing climate change. This transition is critical not only for reducing emissions but also for ensuring energy security and creating sustainable, low-carbon economies in the future. As the world accelerates its push toward a greener, more resilient energy system, hydrogen’s role as an energy vector will continue to grow, unlocking new opportunities for innovation and collaboration across the globe.
1.3 Why Hydrogen? Comparison with Fossil Fuels and Renewables
1.3.1 Hydrogen vs. Fossil Fuels
Table 1.3 compares the characteristics of hydrogen with fossil fuels (gasoline and natural gas) and lithium-ion batteries, focusing on key aspects such as emissions, energy efficiency, energy density, and transport/storage capabilities. This comparison provides valuable insights into how hydrogen fares against traditional and emerging energy carriers in terms of sustainability, cost-effectiveness, and performance. The table below highlights these differences:
Table 1.3 Comparison of hydrogen with other energy carriers (electricity, natural gas, gasoline) in terms of energy density, emissions, and efficiency.
Characteristic
Hydrogen
Gasoline
Natural gas
Lithium-ion batteries
Energy density (per kg)
120 MJ/kg
44 MJ/kg
53 MJ/kg
150–200 Wh/kg (0.54–0.72 MJ/kg)
Energy density (per L)
0.0108 MJ/L (at 700 bar)
33.6 MJ/L
22.8 MJ/L
~0.25–0.5 MJ/L
Emissions (CO
2
equivalent)
Zero emissions (when used in fuel cells)
2.31 kg CO
2
/L (per liter of gasoline)
1.85 kg CO
2
/m
3
(natural gas)
Zero emissions at point of use (electricity production emissions vary)
Efficiency
50–60% (fuel cells), up to 90% with heat recovery
20–30% (internal combustion engine)
30–35% (fossil fuel power plants)
85–90% (for electric vehicles and stationary applications)
Storage
Requires high pressure (700 bar), cryogenic storage (−253 °C), or metal hydride storage
Stored as liquid or vapor at standard temperature and pressure
Stored in pressurized containers, or liquefied for transport
Stored as chemical energy in cells (solid state)
Transport
High-pressure cylinders, pipelines, or liquid transport
Trucks, pipelines, tanks
Pipelines, trucks, LNG
Transported in individual cells or packs
Cost (per kWh)
~$4–$6 (green hydrogen)
~$0.10–$0.25 (depending on region)
~$0.04–$0.10 (depending on region)
~$0.12–$0.18 per kWh
Availability
