Page 275 - Materials Chemistry, Second Edition

10 Life Cycle Impact Assessment 261

Several classification schemes exist for resources (Lindeijer et al. 2002), clas-
sifying them according to their origin into Abiotic resources (inorganic materials—
e.g. water and metals, or organic materials that are non-living at the moment of their
extraction—fossil resources) and Biotic resources (living at least until the time of
their extraction or harvest from the environment, and hence originating in the
biomass). A further classification may be done according to the ability of the
resource to be regenerated and the rate by which it may occur. Here resources are
classified into:
• Stock resources exist as a finite and fixed amount (reserve) in the ecosphere and
are not regenerated (metals in ores) or regenerated so slowly that for practical
purposes the regeneration can be ignored (fossil resources)
• Fund resources regenerate but can still be depleted (like the stock resources) if
the rate of extraction exceeds the rate of regeneration. Depletion can be tem-
porary if the resource is allowed to recover but it can also be permanent for
biotic fund resources where the species underlying the resource becomes extinct.
Biotic resources are fund resources but there are also examples of abiotic re-
sources like sand and gravel where the regeneration rate is so high that it is
meaningful to classify them as fund resources
• Flow resources are provided as a flow (e.g. solar radiation, wind and to some
extent freshwater) and can be harvested as they flow by. Flow resources cannot
be globally depleted but there may be local or temporal low availability (notably
for freshwater—see Sect. 10.15)
Stock resources are also referred to as non-renewable resources while fund and
flow resources jointly are referred to as renewable resources. Resources may also
be classified as exhaustible, i.e. they can be completely used up, and inexhaustible,
which are unlimited.

10.16.3 Existing Characterisation Models

Impacts resulting from resource use are often divided into three categories fol-
lowing the impact pathway (see Fig. 10.28):
1. Methods aggregating natural resource consumption based on an inherent
property
2. Methods relating natural resource consumption to resource stocks or availability
3. Methods relating current natural resource consumption to consequences of
future extraction of natural resources (e.g. potential increased energy use or
costs).

Category 1 methods focus for example on exergy [expressing the maximum
amount of useful work the resource can provide in its current form, (Dewulf et al.
2007)], energy (Frischknecht et al. 2015) and solar energy (Rugani et al. 2011).