The first one is
based on the uptake of CO2 or other organic substrates and water
by photosynthetic organisms. Its major drawbacks are the requirement of a constant light source supply and the low yields of the overall process [5]. Dark fermentation consists in the conversion of
sugars into H2, CO2 and organic acids by microorganisms, through
the acidogenic pathway. Theoretically, any sugar-containing biomass can be used as a feedstock [6] and if the chosen biomass is readily available and lost-cost, the appeal of the process could be
increased.