Hydrogen Generation by Water Splitting

Abstract

Hydrogen is the most abundant element in the universe. Hydrogen is found as interstellar gas and as the chief constituent of main sequence stars. Hydrogen production by partial oxidation from methane increases with process temperature but reaches a plateau value at around 1000 K. The conversion of electric energy into hydrogen by water electrolysis has been known for a long time, but if the electricity is produced using fossil fuels, the cost of hydrogen obtained is higher than the one associated with steam reforming of natural gas. Production of hydrogen from biomass may be achieved by biological fermentation or other bacterial or algae decomposition of water or another suitable substrate. Growing the biological substance in the first place requires energy input, normally from sunlight, and there are several conversion efficiencies involved: from primary energy source to biological material, from energy in biological material to energy in the hydrogen produced, or the overall efficiency from solar radiation to hydrogen.