LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 5B: METHODOLOGICAL CHALLENGES FOR CROP PRODUCTION SYSTEMS8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
3. Results
3.1. Case study for the Cereal Unit as allocation procedure
A comparison of allocation approaches was elaborated for selected agricultural products from cereal-,
sugar- and oilseed-sector (Figure 2). For example, the environmental burden of a barley plant is allocated to
barley grain and straw as follows: when mass allocation is applied, 56% is allocated to the grain and 44% to
the straw; when energy allocation is used, 55% is allocated to the grain and 45% to the straw; when economic
allocation is used 95% is allocated to the grain and 5% to the straw; when the Cereal Unit allocation is
applied 77% is allocated to the grain and 23% to the straw. The results of Cereal Unit allocation are well
between the outcomes of mass-, energy- and economic allocation.
Figure 2. Comparison of mass-, energy-, economic- and Cereal Unit allocation for selected agricultural products;
the sizes of bars indicate the allocation ratio between the environmental burden of the first product and
the total environmental burden
4. Discussion
Usually the users of agricultural LCA results typically deal with different agricultural products. For the
sake of credible results, it is their aim to treat all products and by-products as fairly and as adequately as
possible. This aim could be achieved by a reliable allocation solution for all agricultural processes. This is
crucial to improve the credibility of LCA results in agriculture. The way of allocating environmental burden
in agricultural LCAs or within LCAs for products derived thereof, is crucial for the results, because allocation
steps often take place several times. Errors introduced by each allocation step propagate. This emphasises
the necessary accuracy of allocation approaches for convincing LCA results.
Cereal Unit conversion factors already are available for a large number of agricultural crops and their byproducts
(BMELV, 2012; Mönking et al., 2010). A suitable allocation method both for products and byproducts
allows LCA practitioners to use the same allocation method within independent LCAs – even if the
practitioners do not know each other. For that reason the Cereal Unit allocation approach is suitable regardless
of the product’s final use. The suitability of the Cereal Unit for all products and by-products helps to
avoid the use of different allocation methods within one product system and therefore avoids an unintended
ignorance or double counting of environmental burden.
Agricultural production includes both vegetable and animal production. In many product systems animal
and vegetable production are interlinked. Because the Cereal Unit is valid for vegetable and animal products,
it allows LCA modellers better to depict agricultural reality. An artificial split between of crop and livestock
farming becomes no longer necessary.
If Cereal Unit conversion factors are not yet available for a particular product, they can be developed
based on the published calculation method (BMELV, 2012; Mönking et al., 2010). In a strict sense, the existing
factors are valid for Germany only, because livestock composition and feed consumption of the region
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