Photofermentation: Harnessing solar energy for biohydrogen production

Due to the increase in the world's population and industrial progress, the growing energy needs of our planet have become a serious issue in the face of critical environmental problems. Conventional energy sources, especially fossil fuels, are mostly used today. However, they are not only limited but also cause a lot of harmful effects on the environment due to high greenhouse gas emissions. Hydrogen (H2) is an increasingly energy source, as it has a high energy content and only produces water when perfectly combusted. One example of sustainable and clean energy solutions is the photofermentative production of biohydrogen. In this process, microorganisms that produce hydrogen gas from solar energy use various organic substrates as starting material. This in turn helps one to reduce carbon emissions using solar energy and provides a recycling solution for organic waste—encouraging people to look at waste reduction and to use concepts such as environmental sustainability. Various aspects such as the choice of microorganisms and substrates used or the process parameters under different types of operational monitoring influence biohydrogen production through photofermentation. All together contribute to optimize the production efficiency of biohydrogen and thus the industrial scaling. This chapter addresses the physiological aspects of the photosynthetic enzymes, the reaction time required for the surfactant biosurfactants to be incorporated in excess into the fermentation broth, and the biocatalyst during the photofermentation process. This part deals with the metabolic pathways of microorganisms, the design and optimization of bioreactors, and the operational difficulties encountered when scaling up these systems.