Abstract
Background, aim and scope After China and India, Thailand
is considered another emerging market for fuel ethanol
in Asia. At present, ethanol in the country is mainly a
fermentation/distillery product of cane molasses, although
cassava and cane juice are considered other potential raw
materials for the fuel. This study aims to evaluate the
environmental impacts of substituting conventional gasoline
(CG) with molasses-based gasohol in Thailand.
Materials and methods The life cycle assessment (LCA)
procedure carried out follows three interrelated phases:
inventory analysis, characterization and interpretation. The
functional unit for the comparison is 1 l gasoline equivalent
consumed by a new passenger car to travel a specific
distance.
Results The results of the study show that molasses-based
ethanol (MoE) in the form of 10% blend with gasoline
(E10), along its whole life cycle, consumes less fossil
energy (5.3%), less petroleum (8.1%) and provides a
similar impact on acidification compared to CG. The fuel,
however, has inferior performance in other categories (e.g.
global warming potential, nutrient enrichment and photochemical
ozone creation potential) indicated by increased
impacts over CG.
Discussion In most cases, higher impacts from the upstream
of molasses-based ethanol tend to govern its net life
cycle impacts relative to CG. This makes the fuel blend less
environmentally friendly than CG for the specific conditions
considered. However, as discussed later, this
situation can be improved by appropriate changes in energy
carriers.
Conclusions The LCA procedure helps identify the key
areas in the MoE production cycle where changes are
required to improve environmental performance. Specifically,
they are: (1) use of coal as energy source for ethanol
conversion, (2) discharge of distillery spent wash into an
anaerobic pond, and (3) open burning of cane trash in sugar
cane production.
Recommendations and perspectives Measures to improve
the overall life cycle energy and environmental impacts of
MoE are: (1) substituting biomass for fossil fuels in ethanol
conversion, (2) capturing CH4 from distillery spent wash
and using it as an energy supply, and (3) utilizing cane trash
for energy instead of open burning in fields.