Page 146 - Materials Chemistry, Second Edition

9 Life Cycle Inventory Analysis 131

Is the production of the product constrained?
•Is it produced as a low-value by-product?
•Is its production constrained by regulation?
•Is its production physically constrained?
•…
No
Yes Go to Step 4
Will the demand increase or decrease as
result of decision?
Increase Decrease
Is the product already used to the extent Is the product already used to the extent
the constraint allows? the constraint allows?
Yes No Yes No

Is the product a low value by-product? Is the product a low value by-product?
Yes No Yes No
Other user finds Waste is Production is Other user uses Waste is Production is
substitute reduced. increased. Go product instead of increased. decreased. Go
to Step 4 alternative to Step 4
Include the Include the
(product
reduced waste modelled as if increased (product
handing in waste handing modelled as if
uncon- uncon-
LCA. in LCA.
strained). strained).

Study market to identify what the product
substitutes/is substituted with – handled in
Step 3

Fig. 9.4 How to identify constrained production and how to handle it

In each of these cases, we need to identify the substitutions that occur in the
market, like in the above example where gas substitutes oil. The question that we
will address in this step of the consequential LCI is: “How do we identify which
product substitutes which?”
In order to identify which products can substitute which, there are two aspects
that we have to consider:
• The products must deliver the same service(s) for the product user.
• The product working as a substitute has to be available.
Below we will address each of these two issues.
Identifying a satisfying substitute for the product user
A product may provide different services for different users, implying that one
product may be a fully satisfying substitute for one user, but completely useless for
another. Thus, to identify which product can substitute which, we first need to
identify the product user who is likely to find a substitute due to an increase in