Page 293 - Materials Chemistry, Second Edition

284 D. Rathore et al.

impact of bioenergy on biodiversity, despite an existing accurate methodology
(Michelsen 2008).
Tokunaga et al. (2012) concluded that by ignoring emissions associated with
land-use change, significant emissions savings could achieve via biofuel use,
ranging from 10 to 80 % reductions than fossil fuel emissions. The land-use
changes could significantly increase life cycle emissions, while byproduct credits
could significantly reduce life cycle emissions. Emmenegger et al. (2011) reported
that the use of marginal arid land for cultivation reduces land-use impacts but
induces a higher demand for irrigation, which finally compensates for the envi-
ronmental benefits. Emmenegger and co-worker concluded that changing from
petrol to biofuels results in a shift of environmental burdens from fossil fuel
resource depletion to ecosystem quality damages.

4.8 Sensitivity Analysis

The key purpose of sensitivity analysis is to identify and focus on key data and
assumptions that have the most influence on a result. It can be used to simplify data
collection and analysis without compromising the robustness of a result or to
identify crucial data that must be thoroughly investigated. According to IFEU
(2000), the sensitivity analysis can typically be carried out in three ways, i.e., data
uncertainty analysis, different system boundaries, and different life cycle com-
parisons. The identification of lower and upper values of the process parameters
could introduce subjectivity to the analysis and will reflect better on the charac-
teristics of the parameter analyzed (Fukushima and Chen 2009).
Reap and co-workers summarize their opinions about severity and solution
adequacy using a simple ordinal scale (Table 3). ‘‘Each number represents a

Table 3 Problems in LCA qualitatively rated by severity and adequacy of current solutions (1,
minimal severity while 5, severe; 1, problem solved while 5, problem largely unaddressed)
(adapted from Reap et al. 2008b)
Problem Severity Solution adequacy
Functional unit definition 4 3
Boundary selection 4 3
Alternative scenario considerations 1 5
Allocation 5 3
Negligible contribution criteria 3 3
Local technical uniqueness 2 2
Impact category selection 3 3
Spatial variation 5 3
Local environmental uniqueness 5 3
Dynamics of the environment 3 4
Time horizons 2 3
Weighting and valuation 4 2
Uncertainty in the decision process 3 3
Data availability and quality 5 3