There are some differences in cassava fresh root yields . Our study applied the average national
fresh root yield in 2010 of 17.17 ton ha-1 while the others used much higher yields ranging from 27
to 39 ton ha-1 for a specific provincial site [31], under the author’s assumption [24], or from the
literature [22]. Given constant farm input energy, the higher yield is applied, the less energy is spent
on per liter of ethanol. The differences in labour energy are explained by the choice of working days
incurred and conversion ratios. Our study applied 81 working days ha-1 equivalent to 648 hours ha-1
while the figures in [31] and [22] are 1,920 and 433 hours ha-1, respectively. A conversion ratio of
2.3 MJ hour-1 is mostly used, while 12.1 MJ hour-1 is applied in [22]. As for the biogas utilization
for steam production, the energy intensity of ethanol industry is not very different among different
studies.