Using the above data, the theoretical energy yields of both
fermentation routes can be calculated as shown in Table 1. Taking
LHV as basis for comparison, by combusting hydrogen obtained
from 1 kg of sucrose, 17% more heat is released in comparison to
that released from the combustion of the corresponding amount of
ethanol (24% more heat if HHV is taken as a basis). Although the
theoretical results cannot be extrapolated to industrial conditions
where the reaction efficiencies always are less than 100% and can
be different for the different reactions, the prospect of increased
energy yield of two-stage hydrogen fermentation as compared
with that of ethanol fermentation deserves a closer investigation.