Carbon neutrality and hydrogen energy systems

This review delves into the critical role of hydrogen and its derivative, ammonia, as primary energy vectors pivotal to achieving global carbon neutrality. It highlights hydrogen's unique properties, its innovative production from renewable resources, and its diverse applications across various sectors. Amid the intensifying climate crisis, hydrogen appears as a key player in steering the transition toward sustainable energy paradigms, offering solutions for clean energy generation, efficient storage, and effective distribution. Notably, generating green hydrogen and green ammonia through processes such as water electrolysis, using renewable energy sources, stands at the forefront of strategies aimed at reducing greenhouse gas emissions. This alignment with the global initiative to combat climate change meets the ambitious goals set by international agreements like the Paris Agreement. The review further explores hydrogen's potential in facilitating the integration of intermittent renewable energies into the energy grid, thereby decarbonizing sectors that are challenging to electrify. Moreover, it showcases hydrogen cities as exemplars of sustainable urban development and discusses the roles of hydrogen and ammonia in advancing carbon-neutral solutions in areas where direct electrification is impractical. Special attention is given to the advancements in hydrogen production methods, such as photocatalytic water splitting and high-temperature electrolysis, and their impact on achieving carbon neutrality. The review underscores ongoing research and development efforts in hydrogen and ammonia technologies as essential pathways toward realizing a sustainable, carbon-neutral future.