Page 149 - Materials Chemistry, Second Edition

134 A. Bjørn et al.

can be sold on the glycerol market, it therefore needs to be distilled. In this case,
and in others where additional treatment is needed for the product to be considered
as a substitute, these additional treatments need to be included in the LCI. Also, it
should be noted that in some cases a product substitution may create a cascading
substitution effect (not captured by Fig. 9.5 for simplicity). E.g. if a decrease in
demand for product A leads to other users using product A instead of B (substi-
tutes), which is a waste product that is fully used (nothing goes directly to waste
management), this can lead to other users using product B instead of C (substitutes),
and so on and so forth.

Step 4: Identify production technology affected by change in demand
If the product for which the demand is changed is not limited in supply, it will
normally be assumed in a consequential LCI that supply follows demand in a
one-to-one relationship. The question is, however, which production technology
will be affected by the change in demand. Identifying this technology is the purpose
of this step.
In many cases, similar products can be produced with very different environ-
mental impacts. Just think of electricity that may be produced from wind turbines or
coal fired power plants. It is therefore in many cases important to identify not only
that the production of a certain product will change as a result of the assessed
decision, but also to identify as accurately as possible which supplier, and hereby
which production technology will be affected by the change in demand.
For doing so, three issues need consideration: The size of the change in demand
created by the decision, the trend in the market and whether the assessed decision
leads to an increase or a decrease in demand. These issues will be discussed below.

Size of change
When identifying which technology will be affected by the change in demand, it
is important to distinguish two different perspectives: The immediate production
perspective and the perspective relating to changes in production technologies in
the market. Consider the following example of electricity generation: Some tech-
nologies cost more to run than others. The production of electricity from gas
turbines is, for example, often more expensive than electricity produced from coal.
This implies that only coal power will be used, when the capacity of the installed
coal power plants is sufficient to cover the demand. However, when the demand
increases above what can be supplied by the coal power plants, gas power plants
will start to produce. From an immediate production perspective, the concrete
technology that will supply the demand will depend on the cost efficiency of the
production technologies with available production capacity—the least cost efficient
will be only be used to supply peak load.
However, this is only the immediate consequence of the decision. If the elec-
tricity consumption in the given market in general is increasing or stable, a decision
leading to an increase in demand will push for an increase in the installed power
production capacity. In other words, the decision will have an effect on installed