Life cycle assessment of milk production

Abstract

Life Cycle Assessment (LCA) is a tool for evaluating and quantifying the environmental impact in the production chain of consum products and services. LCA can propose improvements in the productive processes and consequently help to reduce the impacts. Milk production causes environmental impacts on a regional and global scale. We evaluated, in chapter 1, two milk production farms by applying the LCA methodology, aiming to evaluate the role of the anaerobic digester in the LCA of milk production as mitigation of the environmental impacts. One farm performs the treatment of effluents by anaerobic digestion, the Embrapa farm, we performed the analysis on this property with and without the anaerobic digester (AD and NAD1, respectively). The second is the Colinas farm that does not contain the anaerobic digester (NAD2). In addition, in order to investigate whether the choice of software influences the results of LCA, in chapter 2 our study aimed to compare two software. One is the only open source software, OpenLCA® 1.6.3., and another is commercial software, most used worldwide, SimaPro® 8.5.2. For this comparison, we used the LCA of the AD and NAD2 scenarios. The farms are in the state of Minas Gerais, Brazil. We adopted 1 kg of fat and protein milk corrected as functional unit. To assess of environmental impacts, and to compare the software tools, the method CML 2001 (baseline), version 4.4, was used considering the following categories of impact: potential acidification, ozone depletion, energy use, eutrophication, climate change and photochemical oxidation. The anaerobic digester is a good alternative to reduce the environmental impact in all categories evaluated. DA has lower potential impact for acidification, eutrophication, climate change, energy use, photochemical oxidation, and ozone depletion, on average 25% and 38% than NAD1 and NAD2, respectively. In a qualitative way, the SimaPro and OpenLCA software has friendly interface for modeling and offer practically the same resources. Quantitatively, the SimaPro software presented results different from OpenLCA, for AD scenario, in most of the impact categories, where the "avoided product", feature used in both software tools, may be the main cause of the difference. The results of the NAD2 scenario were similar in both software. The climate change category was the one that presented the closest value in both software and scenarios. We conclude that both software can be applied to perform LCA of dairy production, and attention should be paid to the use of the "avoided product" function. In addition, the presence of the anaerobic digester reduces all the evaluated impacts significantly.