Water footprint and regionalization: the case study of Walloon corn

Corn is an important cereal with a lot of applications in the feed and food industries (e.g. starch production). To evaluate properly the environmental impact of its applications, for example in the growing context of biobased products, a better understanding of the impact of its production is needed, using Life Cycle Analysis (LCA). The studied system is the production of corn in Wallonia (South of Belgium), whose the primary data are taken from Van Stappen et al (2018. Sensitive parameters in local agricultural life cycle assessments: the illustrative case of cereal production in Wallonia, Belgium. Int J Life Cycle Assess 23 2: 225–250). The functional unit is 1 hectare of corn crop in Wallonia. The LCI data are based on actual agricultural practices recorded in farms’ accounting data. The system has been modelled in GaBi 8 using GaBi datasets. The ILCD recommended method has been used. To have a better understanding of water depletion, some other methodologies have been tests for this specific impact categorie such as ReCiPe and the AWARE model.
The part of water resources depletion using ILCD recommended method that is not due to the fertilizers (20 %) production is mostly related to the electricity used for maize drying and storage (70 %), especially associated with nuclear electricity (cooling needs). This is not the case if another method is used for assess the water depletion, if AWARE method is used, most of the impact is coming from fertilizers production and from mechanization (due to the use of on unspecified flow for water consumption), whereas, using ReCiPe, most of the impact is from fertilizers production only.
A study of the water origin has been realized using AWARE and ILCD recommended method and underline the large variety of results. The share of nuclear electricity in water depletion is really high when using ILCD recommended method, therefore special attention has been put on this process.: we have compared the GaBi dataset with the Ecoinvent dataset. For the Ecoinvent dataset the calculation have been realized in GaBi but also in Simapro. This comparison is realized for the three method investigate there and underlines large differences between software.
Therefore, this contribution allows to underline the difference between method for water depletion calculation but also the differences induced by regionalized or not regionalized datasets and also underline the problem of results that are dependant of the softawre.