Clearly from the figure, economic allocation assigns a major
portion of GHG emissions to sugar, largely leaving aside its coproduct
molasses: 90.1% versus 9.9% and 94.7% versus 5.3% under
the condition with and without the effect of ethanol demand (i.e.
after and before the promotion of molasses for ethanol), respectively.
It is not surprising since molasses has, in any case, little economic
value compared to sugar as a food product for human
consumption. In the context of oil price hikes, molasses has found
a new use as a feedstock for ethanol, but even so, its value still represents
only 26% of that of sugar (see Section 2.3.2). If the price
were determined based on energy content, molasses would be
charged at a cost of 69% of that of sugar (see also Section 2.3.2).
Allocation based on mass/energy content distributes the GHG burden
between sugar and molasses at a ratio of 77:23, i.e. more emissions
are allocated to molasses in this allocation approach than in
economic approach. System expansion, where the co-production of
molasses is assumed to displace the production of animal feed, e.g.
wheat, results in an emission rate of 13.6 kg CO2e/45 kg molasses
which corresponds to 34% of the emission rate assigned to molasses
and sugar, 39.9 kg CO2e/t cane.