Hydrogen from Water — The Potential Role of Green Algae as Solar Energy Conversion System

Abstract

The photobiological production of hydrogen is discussed as a promising biological process for solar energy conversion (Weaver et al. 1980; Hall 1982). The H2 photoproduction of green algae represents one of those possibilities to convert solar energy in a storable and useful fuel. But H2 photoproduction by green algae, as a consequence of its extreme sensitivity to oxygen, is hampered for economical and technological applications. Furthermore, the basic mechanism of the algal photosynthetic reaction is not yet clear. H2 photoproduction may be based on a pure photosynthetic process including photolysis of water as ultimate source of electrons and protons for hydrogen or, on the other hand, H2 photoproduction may be based on a kind of light supported fermentation of organic substrates. Because of the better solar light conversion efficiency the prospects for a practical application of H2 photoproduction by green algae would become better if water could get established as the original source of hydrogen produced.