10.3 Life Cycle Assessment
249
10.3.3 Impact Assessment (Phase 3)
In the next phase, the total amounts of material and energy flows from the LCI
can be placed within impact categories to estimate their impacts. For this, different
LCI databases can be used that provide characterization factors for each flow and
for each impact category. Here, impact characterization factors compiled within the
Ecoinvent database version 3.5 will be used (Wernet et al., 2016).
Table 10.5 provides characterization factors from the database for each of the
material and energy flows considered. The factors describe the midpoint indicators
of climate change using global warming potential (GWP) through the IPCC 2013
100-year method, cumulative energy demand, as well as ecotoxicity and total human
toxicity using the USEtox model (Rosenbaum et al., 2008; Hauschild et al., 2008;
Rosenbaum et al., 2011; Henderson et al., 2011). Notice that the names of the data
sets applied for some reagents and solvents do not match the flows within the system
being reviewed. This is because the development of such inventory databases is
ongoing, and not all products and processes have data available to describe them. In
such cases, it can be necessary to approximate the characterization factors by using
other (similar) products or processes in the database. In this case, the processes
applied may be a significant simplification, and their characterization factors may
underestimate the actual impacts of the more complex reactants used in the reaction.
Note that the incineration of solvents produces some heat and electricity, which
results in them offsetting the need to produce heat and electricity from other energy
sources. This credit is considered within the calculation of the characterization
factors and results in them being negative.
Task: Using the characterization factors provided in Table 10.5 and the data
compiled in the life cycle inventory, calculate the expected impacts. Do this for
each material and energy flow separately, and then total the values for each stream
type (reactant, waste produced, or energy flow) and for each midpoint indicator.
10.3.4 Interpretation (Phase 4)
After completion of the inventory analysis and impact assessment, the results from
the LCA need to be interpreted and used to derive conclusions and recommendations.
Task: Answer the following:
(a) What are the total impacts (climate change, CED, ecotoxicity, and human
toxicity) of this process step to produce 3-amino-2-isopropylthio benzonitrile
if all of the wastes are assumed to be incinerated? Which material or energy
flows have the largest impact? Is this the case across all of the three midpoint
indicators?
249
10.3.3 Impact Assessment (Phase 3)
In the next phase, the total amounts of material and energy flows from the LCI
can be placed within impact categories to estimate their impacts. For this, different
LCI databases can be used that provide characterization factors for each flow and
for each impact category. Here, impact characterization factors compiled within the
Ecoinvent database version 3.5 will be used (Wernet et al., 2016).
Table 10.5 provides characterization factors from the database for each of the
material and energy flows considered. The factors describe the midpoint indicators
of climate change using global warming potential (GWP) through the IPCC 2013
100-year method, cumulative energy demand, as well as ecotoxicity and total human
toxicity using the USEtox model (Rosenbaum et al., 2008; Hauschild et al., 2008;
Rosenbaum et al., 2011; Henderson et al., 2011). Notice that the names of the data
sets applied for some reagents and solvents do not match the flows within the system
being reviewed. This is because the development of such inventory databases is
ongoing, and not all products and processes have data available to describe them. In
such cases, it can be necessary to approximate the characterization factors by using
other (similar) products or processes in the database. In this case, the processes
applied may be a significant simplification, and their characterization factors may
underestimate the actual impacts of the more complex reactants used in the reaction.
Note that the incineration of solvents produces some heat and electricity, which
results in them offsetting the need to produce heat and electricity from other energy
sources. This credit is considered within the calculation of the characterization
factors and results in them being negative.
Task: Using the characterization factors provided in Table 10.5 and the data
compiled in the life cycle inventory, calculate the expected impacts. Do this for
each material and energy flow separately, and then total the values for each stream
type (reactant, waste produced, or energy flow) and for each midpoint indicator.
10.3.4 Interpretation (Phase 4)
After completion of the inventory analysis and impact assessment, the results from
the LCA need to be interpreted and used to derive conclusions and recommendations.
Task: Answer the following:
(a) What are the total impacts (climate change, CED, ecotoxicity, and human
toxicity) of this process step to produce 3-amino-2-isopropylthio benzonitrile
if all of the wastes are assumed to be incinerated? Which material or energy
flows have the largest impact? Is this the case across all of the three midpoint
indicators?