consumption, transport, waste disposal, emissions levels) are
based on this functional unit.
2.2. System boundaries
Fig. 1 presents system boundary which are set using a cradleto-
gate approach. Corn-based and cassava-based ethylene
production scenarios were studied. Co-product allocation
based on product mass was performed. Processes included in
present study are summarized as follows:
1) Corn and cassava production at farm
2) Ethanol and ethylene production
3) Machinery drying
4) Road transport
5) Waste treatment
6) Material and coal based energy production
7) Energy recovery on site
The infrastructure for ethylene production was excluded
because of the lack of detailed information in the present
ethylene production site.
2.3. Methodology
LCA evaluation is calculated using the IMPACT2002þ method
[11], which consistently treats fate exposure in multimedia
modeling. This method is a combination of results of the
IMPACT2002 model for human health [12], Eco-indicator 99