Current Insights to Enhance Hydrogen Production by Photosynthetic Organisms

Hydrogen gas (H 2) is considered to be one of the most important gases on earth; it can be used as an important alternative source of renewable energy. Although the amount of this gas in the Earth's atmosphere is far less compared to other gases, H 2 can be produced in different ways either by physical, chemical, or biological reactions, or obtained from fossil fuels. It can be produced biologically by lower or higher organisms, and this can contribute as an alternative source of H 2 for future generations. For biological H 2 production, bacteria, cyanobacteria, algae, and higher plants are the major organisms that can produce pure H 2 for sustainable usage. In this chapter, we briefly review different methods of production of H 2 and focus on modern studies devoted to photosynthetic production of H 2 by algae and microorganisms.