Optimization of phototrophic hydrogen production by Rhodopseudomonas palustris PBUM001 via statistical experimental design

Hydrogen (H2) is considered as a promising and ideal source of energy for the future. This is due to the factor that it is clean and it produces an amount of energy that is higher than the one produced by other fuel on a mass basis (122 kJ g_1) [1]. In addition, its low heating value (LHV) is 2.4, 2.8 and 4 times higher than methane, gasoline and coal respectively [2]. For these reason, the amount of energy produced during H2 combustion is higher than that released by any other fuel on a mass basis. Besides, significant use of H2 will contribute to the reduction of energy-linked environmental impacts, including global warming due to anthropogenic carbon emissions, mobile source emissions such as CO, NOx, SOx, non-methane hydrocarbons, and particulates [3].