Design, Modeling, and Optimization of Novel Fuel Cell Systems

1. Introduction

Fuel cells have emerged as a cornerstone in the pursuit of sustainable energy solutions [1]. Their high efficiency, adaptability, and low environmental impact make them critical in transitioning to a low-carbon economy [2]. The global interest in innovative fuel cell systems continues to grow, driven by rising energy demands and the imperative to reduce carbon emissions [3,4]. As efficient energy conversion becomes increasingly important across various sectors, fuel cell systems are emerging as versatile solutions for residential, industrial, and commercial applications, including stationary, vehicular, and mobile uses [5]. While fuel cells can operate on diverse fuel types, they are particularly valued for enabling the conversion of green electricity into hydrogen [6,7]. This green hydrogen can be stored and later used in fuel cells when green electricity is unavailable.

This Special Issue aims to highlight advancements in the design, modeling, and optimization of next-generation fuel cell systems. It includes contributions from all aspects of fuel cell technology, with a focus on system-level studies. The published work explores areas such as thermodynamics, computational fluid dynamics, electrochemistry, as well as economic and environmental analyses. Moreover, it includes research that integrates theoretical and experimental approaches. It also includes studies that are focused on the integration of renewable energy sources (RES) with fuel cell technologies and other alternative or conventional technologies, emphasizing the growing interest in advanced energy systems that can reach multiple objectives, related to environmental, economic, and technical aspects.

This editorial highlights the significant contributions presented in the Special Issue titled “Design, Modeling, and Optimization of Novel Fuel Cell Systems”, published in Energies. The aim of this Special Issue was to address key challenges in fuel cell technologies, explore advanced modeling and optimization strategies, and present novel applications. The articles included in this Special Issue delve into diverse topics, such as the integration of fuel cells with hybrid systems, advancements in proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC) technologies, and innovative approaches to thermal management. Together, these studies reflect the interdisciplinary nature of fuel cell research and its potential to transform energy systems globally.

The articles presented in the Special Issue are useful for researchers, engineers, and students who work with novel fuel cell systems.

2. Review of Advances

Fuel Cell Modeling and Optimization: Modeling and optimization are vital in improving fuel cell performance and addressing operational challenges. Kukk et al. [8] investigated the long-term stability of SOFC materials under different operational modes, shedding light on critical degradation mechanisms that hinder commercialization. In a related study, Choi et al. [9] employed electrochemical impedance spectroscopy to separate resistances in PEMFCs, enabling a better understanding of operational inefficiencies. Encalada-Dávila et al. [10] explored the use of nature-inspired algorithms to optimize PEMFC polarization curves, emphasizing the role of environmental parameters like relative humidity. Meanwhile, Diab et al. [11] developed a continuous-discrete extended Kalman filter to estimate PEMFC parameters in real time, enhancing dynamic performance. Zhao et al. [12] proposed an adaptive optimization approach for direct methanol fuel cells, using a BP neural network and whale optimization algorithm, improving fuel cell performance through optimal operating parameter evaluation and adjustment.

Hybrid and Integrated Systems: The integration of fuel cells with other energy technologies is critical for achieving energy efficiency and reducing emissions. Calise et al. [13] conducted dynamic simulations of a hybrid system combining photovoltaics, fuel cells, and hydrogen storage, demonstrating substantial energy savings and emission reductions. In the field of aviation, Jarry et al. [14] highlighted the benefits of fuel cell–battery hybrid systems, improving aircraft efficiency while extending the operational life of fuel cells. Unmanned aerial vehicles (UAVs) have also benefited from fuel cell optimization. Alrayes and Gadalla [15] developed a multi-design framework for optimizing fuel cell-powered UAVs, significantly enhancing flight endurance. Similarly, Toghyani et al. [16] investigated PEMFC-based UAVs, focusing on unblocked bean-shaped design as an option for aerial applications, while Fragiacomo et al. [17] explored hybrid hydrogen-battery powertrains for rail transport, highlighting their potential in decarbonizing regional rail systems.

Thermal and Water Management: Effective thermal and water management is essential for maintaining fuel cell performance and reliability. Hmad and Dukhan [18] demonstrated the use of metal foam in air-cooled PEMFC stacks, presenting a novel cooling strategy that improved heat dissipation. Mularczyk et al. [19] explored water evaporation limitations in PEMFC gas diffusion layers, emphasizing the importance of efficient water removal for enhanced durability. Khan et al. [20] provided experimental insights into optimized gas supply and anode purging strategies for PEMFC systems. Their findings demonstrated how improved reactant management could reduce parasitic losses and boost overall efficiency, paving the way for more robust fuel cell designs.

Applications and Advanced Systems: Fuel cells continue to find innovative applications across various industries. Samsun et al. [21] developed a diesel-based auxiliary power unit for practical applications, achieving target power densities and start-up times suitable for industrial use. Toghyani et al. [16] introduced a bean-shaped flow field design for PEMFCs, optimizing power density and thermal management for UAVs. Arsalis et al. [22] reviewed progress in hybrid photovoltaic–hydrogen microgrid systems, discussing integration challenges and proposing solutions for enhanced system performance. Oh et al. [23] optimized membraneless microfluidic fuel cells, achieving substantial performance improvements through advanced channel geometry. Finally, Wang and Spatschek [24] used phase-field modeling to analyze chromium oxide layer growth in SOFC interconnects, addressing long-term degradation issues and improving material resilience.

3. Future Directions

Fuel cells appear to be promising for clean energy applications across transportation, microgrids, and portable power systems. Efforts to enhance their efficiency, cost-effectiveness, and durability are evident through research focused on optimizing materials, structural designs, and operating conditions. For example, advanced modeling and diagnostic tools, such as electrochemical impedance spectroscopy and extended Kalman filters, are being employed to improve real-time performance monitoring and parameter estimation. This progress aims to overcome challenges such as membrane degradation, water management, and resistance losses, paving the way for broader commercialization. Energy storage solutions are increasingly integrated with RES to address the intermittent nature of solar and wind power. Hybrid systems combining photovoltaic cells with hydrogen-based storage are a prominent research focus. These systems utilize electrolysis to generate green hydrogen, which can be stored and converted back into electricity via fuel cells when demand peaks or renewable generation dips. Dynamic simulation studies of such hybrid systems highlight their potential to significantly reduce greenhouse gas emissions while enhancing energy self-sufficiency and flexibility. However, widespread adoption depends on lowering the cost of electrolyzers and fuel cell stacks, as well as improving the efficiency of hydrogen production, storage, and utilization technologies.

The transportation sector is a major area of application for fuel cell and hybrid systems. Innovations include fuel cell-powered UAVs optimized for endurance, lightweight design, and rapid refueling. Similarly, hydrogen-powered and battery-hybrid trains are being developed to replace traditional diesel engines, particularly on non-electrified tracks. These efforts not only aim to reduce emissions but also to improve operational efficiency and adapt to diverse regional infrastructure constraints. Cooling and thermal management systems represent another critical area of innovation. Research into novel materials, such as metal foams for heat dissipation, demonstrates the potential to enhance the performance and longevity of fuel cells by maintaining optimal operating temperatures. These developments are essential as higher power densities and compact designs lead to greater heat generation.

In the broader energy landscape, the integration of fuel cells with decentralized microgrids and hybrid systems signifies a shift toward more localized and resilient energy production. Microgrid systems featuring photovoltaic arrays, hydrogen storage, and advanced energy management strategies are highlighted as solutions for reducing reliance on central grids and enhancing energy security, particularly in remote or underserved regions. These systems are also being explored for their potential to support electric vehicle infrastructure, thus contributing to a holistic decarbonization strategy. Across all applications, the role of optimization algorithms and computational modeling is prominent. These tools are being leveraged to fine-tune system designs, predict performance under varying conditions, and identify optimal configurations for components such as flow channels, catalysts, and storage tanks. Advances in machine learning and nature-inspired algorithms further enhance the precision and efficiency of these optimization efforts.

4. Conclusions

The Special Issue “Design, Modeling, and Optimization of Novel Fuel Cell Systems” has significantly contributed to advancing the understanding and application of fuel cell technologies. The advancements highlighted in this collection of studies underline the transformative potential of fuel cell technologies across various domains, driven by progress in modeling, optimization, and integration with other energy systems. Modeling and optimization efforts, including the use of nature-inspired algorithms, machine learning, and real-time parameter estimation, are paving the way for enhanced fuel cell efficiency, reliability, and operational performance. Studies demonstrate the critical role of understanding degradation mechanisms and leveraging advanced computational tools to address operational inefficiencies. The integration of fuel cells with RES-based equipment and hybrid configurations has emerged as a promising avenue for achieving significant energy savings and emission reductions. Research on hybrid systems, such as fuel cell–photovoltaic combinations and hydrogen storage, showcases their potential in diverse applications, from aviation and marine systems to rail transport. These innovations underline the need for continued exploration of hybrid and multifunctional systems that capitalize on complementary technologies. Thermal and water management remains pivotal for sustaining fuel cell performance. Novel strategies, including the use of metal foams and advanced gas diffusion layer designs, have demonstrated significant improvements in durability and efficiency. The application of fuel cells across industries continues to expand, with developments in UAVs, rail transport, microfluidic fuel cells, and auxiliary power units pointing to their versatility and growing commercial viability.

The articles featured in this Special Issue reflect the interdisciplinary nature of fuel cell research, addressing both technical challenges and real-world applications. These studies provide valuable insights into the design, modeling, optimization, and integration of fuel cells, laying a strong foundation for future developments. The included contributions demonstrate the transformative potential of fuel cells in achieving sustainable energy systems. Future research should prioritize enhancing durability, reducing costs, scaling up hydrogen infrastructure, and standardizing policies to accelerate adoption. Moreover, optimizing integration with RES and exploring innovative hybrid systems will be key to unlocking the full potential of fuel cell technologies.