Fuelling the future: An in-depth review of recent trends, challenges and opportunities of hydrogen fuel cell for a sustainable hydrogen economy

Hydrogen has gained tremendous momentum worldwide as an energy carrier to transit to a net zero-emission energy sector. It has been widely adopted as a promising large-scale renewable energy (RE) storage solution to overcome RE resources' variability and intermittency nature. The fuel cell (FC) technology became in focus within the hydrogen energy landscape as a cost-effective pathway to utilize hydrogen for power generation. Therefore, FC technologies' research and development (R&D) expanded into many pathways such as cost reduction, efficiency improvement, fixed and mobile applications, lifetime, safety and regulations, etc. Many publications and industrial reports about FC technologies and applications are available. This raised the necessity for a holistic review study to summarize the state-of-the-art range of FC stacks, such as manufacturing, the balance of plant, types, technologies, applications and R&D opportunities. At the beginning the principal technologies to compare the well-known types, followed by the FC operating parameters, are presented. Then the FC balance of the plant, i.e., building components and materials with its functionality and purpose, types and applications, are critically reviewed with their limitations and improvement opportunities. Subsequently, the electrical properties of FCs with their key features, including advantages and disadvantages, were investigated. Applications of FCs in different sectors are elaborated with their key characteristics, current status and future R&D opportunities. Economic attributes of fuel cells with a pathway towards low cost are also presented. Finally, this study identifies the research gaps and future avenues to guide researchers and the hydrogen industry.