5.4 Inventory Analysis (Phase 2)
79
The values in the biosphere matrix (B) represent the elementary flows of energy
or resources extracted from or emitted into the environment for each process or
product in the technosphere matrix (A).
Figure 5.10 shows how the values from the process tree are input into the
biosphere matrix. For example, 1.5 kg of rock salt is extracted as a resource from
the environment to produce 1 kg of salt.
Combining the flows within the technosphere with the flows within the biosphere,
these two matrices can be used together with the final product demand vector (f) to
calculate the total elementary flows from and to the environment (y) across all levels
of the process tree:
y = B × (I − A)
−1
× f
(5.2)
Figure 5.10 shows how the elementary flow values from the process tree are input
into the biosphere matrix and used to calculate the total elementary flow vector (y)
for the production of 1 kg of chlorine gas.
Following the same approach as introduced for the technosphere matrix, Fig. 5.10
illustrates how the cumulative emissions of 2.75 kg CO 2 are reached when totaling
along all of the levels within the process tree.
5.4.5 Direct Interpretation of LCI Results
The developed life cycle inventory provides information on the use of materials and
resources (including energy) of the system under investigation, and sometimes it
provides enough information to already highlight some key areas for improvement.
For example, comparing the energy and resource use of a chemical product or
process from the inventory with theoretical optima of the reaction can provide
insight into:
• Energy-saving potential
• Increasing synthesis yield
• Better use of input resources
• Reducing refinement and application losses
• Current capacity bottlenecks
LCI data can sometimes also already be used to compare alternatives. For
example, Fig. 5.11 shows a set of alternative reducing agents that can be used for the
reaction from a monoazo compound to TINUVIN ® . Through the development of an
LCI, the by-products from the reduction reaction can be determined to range from
clearly more hazardous substances such as zinc hydroxide (Zn(OH) 2 ) to benign
substances such as water. Of the three produced by-products, water is the least
reactive and also has the lowest molecular weight. This means that with water, there
will also be a lower quantity of by-product to manage. Considering this, H 2 might be
the better reducing agent to use in this application. However, to achieve a complete
79
The values in the biosphere matrix (B) represent the elementary flows of energy
or resources extracted from or emitted into the environment for each process or
product in the technosphere matrix (A).
Figure 5.10 shows how the values from the process tree are input into the
biosphere matrix. For example, 1.5 kg of rock salt is extracted as a resource from
the environment to produce 1 kg of salt.
Combining the flows within the technosphere with the flows within the biosphere,
these two matrices can be used together with the final product demand vector (f) to
calculate the total elementary flows from and to the environment (y) across all levels
of the process tree:
y = B × (I − A)
−1
× f
(5.2)
Figure 5.10 shows how the elementary flow values from the process tree are input
into the biosphere matrix and used to calculate the total elementary flow vector (y)
for the production of 1 kg of chlorine gas.
Following the same approach as introduced for the technosphere matrix, Fig. 5.10
illustrates how the cumulative emissions of 2.75 kg CO 2 are reached when totaling
along all of the levels within the process tree.
5.4.5 Direct Interpretation of LCI Results
The developed life cycle inventory provides information on the use of materials and
resources (including energy) of the system under investigation, and sometimes it
provides enough information to already highlight some key areas for improvement.
For example, comparing the energy and resource use of a chemical product or
process from the inventory with theoretical optima of the reaction can provide
insight into:
• Energy-saving potential
• Increasing synthesis yield
• Better use of input resources
• Reducing refinement and application losses
• Current capacity bottlenecks
LCI data can sometimes also already be used to compare alternatives. For
example, Fig. 5.11 shows a set of alternative reducing agents that can be used for the
reaction from a monoazo compound to TINUVIN ® . Through the development of an
LCI, the by-products from the reduction reaction can be determined to range from
clearly more hazardous substances such as zinc hydroxide (Zn(OH) 2 ) to benign
substances such as water. Of the three produced by-products, water is the least
reactive and also has the lowest molecular weight. This means that with water, there
will also be a lower quantity of by-product to manage. Considering this, H 2 might be
the better reducing agent to use in this application. However, to achieve a complete