Abstract
The 21st century is poised to become the century of seeking new energy sources and carriers. At present, the world economy heavily relies on fossil fuels as energy carriers and raw materials. Other abundant sources or vectors of energy are used marginally mainly because of the expenses associated with them in addition to the difficulty to store or transport them. One of the promising methods is the conversion of any sort of renewable energy to hydrogen that can be stored or converted to other hydrocarbons for transports. Another promising method is the direct conversion of photon energy (solar) to hydrogen by splitting water to its basic elements. In this chapter, we review the feasibility of some of these alternatives. At present, the only available option to replace fossil fuel is nuclear technology while solar energy, and in particular, solar-driven hydrogen production, is the most promising technology in the near future (2020 and beyond).