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

The global economic growth, the increase in thepopulation, and advances in technology lead to an increment in theglobal primary energy demand. Considering that most of thisenergy is currently supplied by fossil fuels, a considerable amountof greenhouse gases are emitted, contributing to climate change,which is the reason why the next European Union bindingagreement is focused on reducing carbon emissions usinghydrogen. This study reviews different technologies for hydrogenproduction using renewable and non-renewable resources.Furthermore, a comparative analysis is performed on renewable-based technologies to evaluate which technologies are economically and energetically more promising. The results show howbiomass-based technologies allow for a similar hydrogen yield compared to those obtained with water-based technologies but withhigher energy efficiencies and lower operational costs. More specifically, biomass gasification and steam reforming obtained a properbalance between the studied parameters, with gasification being the technique that allows for higher hydrogen yields, while steamreforming is more energy-efficient. Nevertheless, the application of hydrogen as the energy vector of the future requires both the useof renewable feedstocks with a sustainable energy source. This combination would potentially produce green hydrogen whilereducing carbon dioxide emissions, limiting global climate change, and, thus, achieving the so-called hydrogen economy.