ABSTRACT
Hydrogen is the most abundantly found element in the universe. It is estimated that the universe is made up of 92% of hydrogen and 7% of helium. The green energy sources include water, wind, solar, bioenergy, hydrogen, geothermal, and so on. Hydrogen and electricity are the secondary sources of energy and produced from primary natural renewable energies. The use of hydrogen as a fuel results in a decrease in the carbon dioxide emission at the rate of 5%, in comparison to the efficiency measures with petrol-electric hybrid vehicles and other fuels like ethanol. Hydrogen use can be evaluated in terms of the issues of environmental emissions, sustainability, and energy security. Different routes for hydrogen production are as follows: steam methane reforming, partial oxidation of hydrocarbons, electrolysis, and gasification of biomass, pyrolysis of biomass, thermochemical process, and photochemical process. Silicon-based solar cells are currently the most significant energy source and they account for more than 90% of global solar energy sources.
