Hydrogen Production Technologies: From Fossil Fuels toward Renewable Sources. A Mini Review

The global economic growth, the increase in the \npopulation, and advances in technology lead to an increment in the \nglobal primary energy demand. Considering that most of this \nenergy is currently supplied by fossil fuels, a considerable amount \nof greenhouse gases are emitted, contributing to climate change, \nwhich is the reason why the next European Union binding \nagreement is focused on reducing carbon emissions using \nhydrogen. This study reviews different technologies for hydrogen \nproduction using renewable and non-renewable resources. \nFurthermore, a comparative analysis is performed on renewablebased technologies to evaluate which technologies are economically and energetically more promising. The results show how \nbiomass-based technologies allow for a similar hydrogen yield compared to those obtained with water-based technologies but with \nhigher energy efficiencies and lower operational costs. More specifically, biomass gasification and steam reforming obtained a proper \nbalance between the studied parameters, with gasification being the technique that allows for higher hydrogen yields, while steam \nreforming is more energy-efficient. Nevertheless, the application of hydrogen as the energy vector of the future requires both the use \nof renewable feedstocks with a sustainable energy source. This combination would potentially produce green hydrogen while \nreducing carbon dioxide emissions, limiting global climate change, and, thus, achieving the so-called hydrogen economy