Page 436 - Biofuels for a More Sustainable Future

388 Biofuels for a More Sustainable Future

In a similar way, all the elements in the probability matrix can be deter-
mined and the results are presented in Eq. (14.12).
Wheat Corn Cassava
Wheat 0:5000 0 0
(14.12)
Corn 1:0000 0:5000 0:4249
Cassava 1:0000 0:5751 0:5000

After that, the sustainability indices of the three pathways for bioethanol
production can be determined and they are as follows:
3
ð 0:5000 + 0 + 0Þ + 1
2
V 1 ¼ ¼ 0:1667 (14.13)
ð
33 1Þ
3
ð 1:0000 + 0:5000 + 0:4249Þ + 1
2
V 2 ¼ ¼ 0:4042 (14.14)
33 1Þ
ð
3
ð 1:0000 + 0:5751 + 0:5000Þ + 1
2
V 3 ¼ ¼ 0:4292 (14.15)
ð
33 1Þ
Therefore the sustainability indices of the three pathways for bioethanol
production are 0.1667, 0.4042, and 0.4292. Accordingly, the cassava-based
bioethanol production pathway with the sustainability index 0.4292 is the
most sustainable, followed by corn-based and wheat-based with the sustain-
ability indices 0.4042 and 0.1667, respectively. The sustainability order of
the three bioethanol production scenarios determined by the developed life
cycle aggregated sustainability index is consistent with the results determined
by the combination of AHP and VIKOR in the work of Ren et al. (2015b).
In addition, the life cycle aggregated sustainability indices with respect to
cassava-based and corn-based bioethanol production systems are much
greater than that of wheat-based bioethanol production systems, and this
conclusion was also consistent to the results in the work of Ren et al.
(2015b), and they argued that the recognition of cassava-based bioethanol
production system as the most sustainable is robust, and corn-based bioetha-
nol production system could be the most sustainable in some cases when
changing the weights of the criteria for life cycle sustainability assessment
of bioethanol production systems.