About 103.6 kg of sugar and 45.2 kg of molasses are
extracted from 1 tonne of sugar cane (Prasertsri 2006).
Thus, the relative contribution of sugar and molasses to the
economy has the ratio of 8.6:1. Based on this ratio, energy
use and emissions from sugar cane and sugar/molasses
production (including transportation) are allocated between
sugar and molasses at 89.6% and 10.4%, respectively. The
ratio is substantially lower than the 15.0:1 for 2005 derived
by the same allocation method. Escalating molasses price is
the main reason for the large variation in allocation ratio. A
sensitivity analysis has been conducted to see how the results
of the study are affected by changing the allocation ratio.
To enhance crop-based ethanol performance, it is
important to consider opportunities to utilize system coproducts.
With the molasses ethanol system, the three types
of utilizable residues are cane trash in sugar cane
production, bagasse in sugar production and stillage in
ethanol conversion.