Factors affecting the longterm stability of biomass and hydrogen productivity in outdoor photofermentation

Photofermentative Hydrogen Production in Outdoor Conditions

“…While investigating continuous hydrogen production using a fed-batch 90 L pilot tubular photobioreactor in outdoor conditions, Boran et al [64] found that the specific growth rate of R. capsulatus increased exponentially with the total light intensity. Moreover, the growth rate of R.capsulatus YO3 (Hup -) was found to be lower (0.0042 h -1 ) during winter (low light intensity and temperatures) compared to that during summer (high light intensity and high temperature) (0.035 h -1 ) [53].…”

“…Maximum hydrogen production rate of 4.0 L/m 2 /h and light conversion efficiency of 2.2% was obtained. In another continuous hydrogen production study using an 8 L flat plate PBR, Androga et al [53] observed that the daily amount of hydrogen produced decreased with the decreasing daily total global solar radiation (from 4000 Wh/m 2 to 2350 Wh/m 2 ). Avcioglu et al [54] reported similar results using continuous cultures of R.…”

“…The major parameters being physical variations like solar light energy and temperature, which are uncontrolled. These parameters regulate photosynthetic bacterial activity, therefore their daily (day/night cycle), seasonal and geographical variation greatly influence the amount of hydrogen produced [38,45,[51][52][53][54][55]. In addition, other parameters such as PBR type, mode of operation, nutrients, carbon to nitrogen ratio, type and age of the microorganism are critical.…”

“…The cell growth of the PNSB was found to fit the logistic model [4,[58][59][60]. In outdoor operations, cell growth and hydrogen production were indicated to be dependent on the solar light intensity received [45,49,[51][52][53][54]61]. Temperature and the intensity of solar radiation vary daily, seasonally and geographically.…”

“…9 h) and shorter night periods are experienced while during summer, longer daylight periods (circa. 14 h) and shorter night periods are experienced [53]. Excessive light energy leads to photo-inhibition, which in turn reduces hydrogen production efficiency [62,67,68].…”