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330 Biofuels for a More Sustainable Future

Corn-based Cassava-based Wheat-based

Fig. 11.3 The sustainability sequence of the three alternative pathways for bioethanol
production.

After solving programming (11.24), the matrix Z can be determined, as
presented in Eq. (11.25).

12 3
Wheat based 0 0 1
(11.25)
Corn based 1 0 0
Z ¼
Cassava based 0 1 0
According to the meaning of the elements in the final ranking matrix, the
sustainable sequence of the three alternative pathways for bioethanol pro-
duction can be determined, as shown in Fig. 11.3.

4 Discussion

The sustainability of the three alternative pathways for bioethanol produc-
tion from the most sustainable to the least is corn-based, cassava-based, and
wheat-based. It is worth pointing out that the ranking of these three alter-
native pathways for bioethanol production was determined based on the
opinions and preferences of the selected experts, and the results may change
when the stakeholders/decision-makers have been changed. In order to
investigate the influences of the weights of the criteria on the sustainability
sequence of the three alternative pathways for bioethanol production, the
following eleven cases were studied for sensitivity analysis by changing
the weights of the nine criteria:
Case 0: Equal weights—an equal weight (0.1111) was assigned to the
nine criteria;
Case 1–9: a dominant weight (0.3600) was assigned to one of the nine
criteria, and an equal weight (0.0800) was assigned to all the other eight
criteria.
The results of sensitivity analysis are presented in Fig. 11.4. It is apparent
that the sustainability sequence of these three alternative pathways for
bioethanol production may change with the change of the weights of the
criteria for sustainability assessment. In other words, the sustainability
sequence of the three pathways for bioethanol production may change when