The aim is to contribute to a deeper understanding of the differences between the consequential (cLCA) and attributional (aLCA) modeling approaches and to show how the choice between cLCA and aLCA in some cases can be decisive for the outcome of an LCA. We present cradle-to-gate CO2-eq. emissions (carbon footprint) of barley, soybean meal and palm oil and discuss the differences between the cLCA and aLCA methodologies and results.
Dalgaard and Muñoz use food production examples to show why attributional and consequential life cycle assessment can give different results. The poster compares cradle-to-gate greenhouse gas footprints for Danish barley, Brazilian soybean meal and Malaysian crude palm oil. Attributional modelling uses average data and price allocation between co-products. Consequential modelling instead models marginal suppliers and uses substitution to represent products displaced by co-products. The analysis excludes land-use-change effects to keep the comparison manageable.
The reported barley footprint is 43% higher under attributional modelling than under consequential modelling. The consequential soybean-meal result is negative because soybean oil displaces palm oil, creating a credit larger than the emissions from growing and processing soybeans. Palm-oil results differ only slightly: the poster attributes most impacts to the oil in both approaches. The authors conclude that co-product treatment and the inclusion of constrained suppliers can materially affect results. They caution against treating constrained inputs, such as manure, as if demand could increase their supply. The poster illustrates methodological differences; it does not provide a general ranking of food products.
