Hydrogen production by biological processes: a survey of literature

Hydrogen is the fuel of the future mainly due to its high conversion effici ency, recyclability and nonpolluting nature. Biological hydrogen production processes are found to be more environment friendly and less energy intens ive as compared to thermochemical and electrochemical processes. They are m ostly controlled by either photosynthetic or fermentative organisms. Till t oday, more emphasis has been given on the former processes. Nitrogenase and hydrogenase play very important role. Genetic manipulation of cyanobacteri a (hydrogenase negative gene) improves the hydrogen generation. The paper p resents a survey of biological hydrogen production processes. The microorga nisms and biochemical pathways involved in hydrogen generation processes ar e presented in some detail. Several developmental works are discussed. Immo bilized system is found suitable for the continuous hydrogen production. Ab out 28% of energy can be recovered in the form of hydrogen using sucrose as substrate. Fermentative hydrogen production processes have some edge over the other biological processes. (C) 2000 International Association for Hydr ogen Energy. Published by Elsevier Science Ltd. All rights reserved.