This review thoroughly examines recent progress, challenges, and future prospects in the field of alkaline exchange membrane (AEM) electrolysis. This emerging technology holds promise for eco-friendly hydrogen production. It blends the benefits of traditional alkaline and proton-exchange membrane technologies, enhancing affordability and operational efficiencies by utilizing non-precious metal catalysts and operating at reduced temperatures. This study discusses key developments in materials, electrode design, and performance enhancement techniques. It also highlights the strategic role of AEM electrolysis in meeting global energy transition targets, like achieving Net Zero Emissions by 2050. An in-depth exploration of the operational fundamentals of AEM water electrolysis is provided, noting the technology’s early stage development and the ongoing need for research in membrane-electrode assembly assessment, catalyst efficiency, and electrochemical ammonia production. Moreover, this review compiles results on different cell components, electrolyte types, and experimental approaches, providing insights into operational parameters critical to optimizing AEM performance. The conclusion emphasizes the necessity for continuous research and commercialization efforts to exploit AEM electrolysis’s full potential across diverse industries.

Unmanned aerial vehicles (UAVs) have become an integral part of modern life, serving both civilian and military applications across various sectors. However, existing power supply systems, such as batteries, often fail to provide stable, long-duration flights, limiting their applications. Previous studies have primarily focused on battery-based power, which offers limited flight endurance due to lower energy densities and higher system mass. Proton exchange membrane (PEM) fuel cells present a promising alternative, providing high power and efficiency without noise, vibrations, or greenhouse gas emissions. Due to hydrogen’s high specific energy, which is substantially higher than that of combustion engines and battery-based alternatives, UAV operational time can be significantly extended. This paper investigates the potential of PEM fuel cells as an alternative power source for electric propulsion in UAVs. This study introduces an adaptive, fully functioning PEM fuel cell model, developed using a reduced-order modeling approach and optimized for UAV applications. This research demonstrates that PEM fuel cells can effectively double the flight endurance of UAVs compared to traditional battery systems, achieving energy densities of around 1700 Wh/kg versus 150–250 Wh/kg for batteries. Despite a slight increase in system mass, fuel cells enable significantly longer UAV operations. The scope of this study encompasses the comparison of battery-based and fuel cell-based propulsion systems in terms of power, mass, and flight endurance. This paper identifies the limitations and optimal applications for fuel cells, providing strong evidence for their use in UAVs where extended flight time and efficiency are critical.

E-fuels, or synthetic fuels produced from green hydrogen and captured CO₂, are a promising solution for achieving climate neutrality by replacing fossil fuels in transportation and industry. They help reduce greenhouse gas emissions and efficiently utilize renewable energy surpluses. This study aims to assess the current state and future potential of e-fuel production technologies, focusing on their scalability and market integration. A comprehensive literature review and market trend analysis, including modeling based on historical data and growth forecasts, were used to estimate market penetration. Results indicate that e-fuels could reach a 10% market share within the next 5 years, potentially reaching 30% in 20 years, particularly in aviation, maritime transport, and the steel industry. Ongoing projects expected to be completed this decade may cover about 20% of the global liquid fuel demand for transportation. However, challenges such as high costs, scalability, and recent project terminations due to funding shortages highlight the need for substantial investment, regulatory support, and innovation. Global collaboration and policy alignment are essential for the successful development and integration of e-fuels as a critical pathway to decarbonization.

High-temperature fuel cells and electrolyzers, particularly molten carbonate fuel cells (MCFCs) and Molten Carbonate Electrolyzers (MCEs), are expected to play a critical role in clean power generation, hydrogen production, and integrated CO₂ separation. Unfortunately, despite their potential, these technologies have not yet reached full commercialization. The main reason for this is material degradation. In particular, the corrosion of metallic components continues to be a leading cause of performance loss and system failure. This review provides a comprehensive assessment of degradation mechanisms in MCFC and MCE systems. It examines key metallic components, such as current collectors and bipolar plates, focusing on the performance of commonly used materials, including stainless steels and advanced alloys, under prolonged exposure to corrosive environments. To address degradation issues, this review evaluates current mitigation strategies and discusses material selection, protective coatings application, and the optimization of operational parameters. Advances in alloy development, coatings, surface treatments, and process controls have been compared in terms of effectiveness, scalability, and long-term stability. The review concludes with a synthesis of current best practices and future directions, emphasizing the need for integrated, multi-functional solutions to achieve the lifetimes required for full commercialization. By linking materials science, electrochemistry, and systems engineering, this review offers directions for the development of corrosion-resistant MCFC and MCE technologies in support of a hydrogen-based, carbon-neutral energy future.

This manuscript discusses the advancements and historical development of solid oxide electrolysis (SOE), co-electrolysis, and methanation technologies, addressing the performance fundamentals and system integration challenges in the context of the EU’s 2050 climate neutrality goals. SOE technologies, characterized by their high efficiencies and ability to operate at elevated temperatures, offer significant advantages in hydrogen production and power generation. Co-electrolysis of steam and carbon dioxide in SOEs provides a promising pathway for syngas production, leveraging carbon capture and utilization strategies to mitigate carbon emissions. Additionally, catalytic methanation processes described within facilitate the synthesis of methane from carbon oxides and hydrogen, which could be integral to renewable energy storage and grid-balancing solutions. Historical analysis provides insights into the evolution of these technologies from early experiments to modern applications, including their role in space programmes and potential for industrial scale-up. The current state of research and commercialization, highlighted through various system designs and operational enhancements, suggests that SOEs are crucial for sustainable energy transformations, underscoring the necessity for continued innovation and deployment in relevant sectors.

The study examines the influence of diverse flue gas compositions on the operational parameters and efficiency of MCFCs (molten carbonate fuel cells) as CO₂ separation devices to provide foundational knowledge on MCFC operation under various industrial conditions. MCFCs inherently rely on the presence of CO₂ at the cathode, where it combines with oxygen to form carbonate ions that migrate through the electrolyte; thus, CO₂ acts as a carrier species rather than a fuel, enabling simultaneous electricity generation and CO₂ separation. The findings indicate that MCFCs are most effective when operated with CO₂-rich flue gases, such as those from coal and lignite-fired power plants with CO₂ contents of roughly 12–15 vol.% and O₂ contents of 2–6 vol.%. In these cases, CO₂ reduction rates of up to 80% can be achieved while maintaining favorable cell voltages. Under such conditions, relevant also for the cement industry (CO₂ between 15 and 35 vol.%), the Nernst voltage can reach about 1.18 V. In contrast, flue gases from gas turbines, which typically contain only 4–6 vol.% CO₂ and 11–13 vol.% O₂, result in lower Nernst voltages (0.6–0.7 V) and a decrease in efficiency. To address this issue, potential modifications to the MCFC electrolyte are suggested to enhance oxygen-ion conductivity and improve performance. By quantifying the operational window and CO₂-reduction potential for different sectors at 650 °C and 1 atm using a reduced-order model, the paper provides a technology assessment that supports sustainable industrial operation and the design of CCS (carbon capture and sequestration) strategies in line with climate goals.