Of different LCA procedures to handle co-products, system
expansion yields the highest estimate of GHG emission load
embodied in molasses, followed by allocation based on mass/
energy content and allocation based on market value. This
explains why the calculation resulting in the worst GHG performance
of ethanol corresponds to the use of system expansion.
However, no matter whether system expansion or allocation
is used, a significant reduction of emissions from ethanol’s fuel
stage in the abatement scenario, combined with a negligible
level of emissions from end use stage, keeps the estimate of
the whole life cycle low enough to support the interpretation
that ethanol is a sustainable alternative fuel.