AGRICULTURAL REFERENCE SYSTEMS IN LIFE CYCLE ASSESSMENTS - Economics of Sustainable Energy in Agriculture - page 102

3. EXAMPLES OF THE INFLUENCE OF
AGRICULTURAL REFERENCE SYSTEMS ON
CALCULATION RESULTS

The potential significance of the reference system on the quantitative
results of calculations within agricultural LCAs can be shown within
various different contexts (Jungk and Reinhardt 2000):
Different reference system options for equal LCA objectives : the
same 'general goal', such as comparing RME versus conventional
diesel, can be achieved using very different reference systems, which
may lead to different results (see Figure 8.3 above).
Different geographical boundaries : in certain cases it may be
desirable to consider only the environmental impacts produced within a
particular country or area. In this case, all ecological impacts caused
outside those boundaries are excluded from the calculations. The
'choice' of the reference system may then have a large impact: if most
of the system is located within the defined boundaries, the impact may
be very different from a situation where the main part of the system
lies beyond the boundaries.
Different combinations of land use producing the same utilities :
different forms of agricultural practice, e.g. conventional and organic
farming, lead to different yields. Thus the surplus areas achieved in
high yield areas can be used for various purposes, such as producing
bioenergy. Through different combinations of farming practices and
the use of bioenergy or fossil fuels, the same commodities (food and
energy) can be produced using different land covers. These
combinations can all be regarded as different reference systems,
leading to different results.
A detailed discussion of each of these issues lies beyond the scope
of this chapter, but the examples in the following three sub-chapters shall
explain the underlying issues of these points in greater depth and thus
clarify some of the main principles associated with the definition of an
appropriate reference system. The calculations in these examples are taken
from and thoroughly explained in the study Jungk and Reinhardt (2000),
which also refers to Borken et al. (1999), Bünger et al. (2000), and
Reinhardt et al. (1999).
Of the ten impact categories generally considered within LCAs, in
the examples shown here five quantifiable categories were chosen:
Energetic resource demand (CED - cumulated energy demand
regarding fossil resources, in J)
Greenhouse effect (expressed as kg regarding

IPCC 1996)