The livestock sector heavily contributes to anthropogenic greenhouse gas emissions especially from enteric fermentation of ruminants, manure management and crop production, but it is also responsible of a large share of ammonia volatilization and nitrate leaching. Life Cycle Assessment (LCA) is a powerful tool to analyze the environmental impact of a product and identify process hotspots. However it is a very complex, time and labor intensive methodology and its results are often affected by different sources of uncertainty. In some contexts a simplified approach could be convenient, provided the accuracy of the results is not compromised. The aim of this study was to compare environmental impacts of milk production obtained from a life cycle analysis using different methodologies for emission estimation at farm level. A group of 29 dairy farms was involved in the study, data were collected through personal interviews to the farmers. On-farm emissions were estimated with a detailed approach using Tier 2 methods from IPCC (2006a,b) and EAA (2009a,b) and with a simplified approach using Tier 1 method from IPCC (2006a,b); the global impact was evaluated with the support of SimaPro software. In general the simplified approach underestimated global warming potential compared to detailed one but slightly overestimated acidification potential; there was no significant difference in terms of eutrophication potential. Overall, even if the simplified approach used fixed values of methane and nitrogen excretion while the detailed approach was based on more specific evaluations, the two methods did not greatly differ in the estimation of total amount of methane and nitrogen lost by the animals. As a consequence very similar impact values were obtained with the two approaches. The simplified approach seems to be a convenient method when a large number of production units are involved in the evaluation. On the contrary the detailed approach is more appropriate for research purposes to identify the different emission sources and their contribution to the impact.
How different emission estimation methods can affect final result? The case of milk production / M. Guerci, L. Bava, A. Sandrucci, M. Zucali, A. Tamburini - In: Life cycle assessment e ottimizzazione ambientale : esempi applicative e sviluppi metodologici / [a cura di] S. Scalbi, F. Reale. - [s.l] : Enea, 2013 Jun. - ISBN 9788882862923. - pp. 14-21 (( Intervento presentato al 7. convegno Convegno della Rete Italiana LCA. Life cycle assessment e ottimizzazione ambientale : esempi applicative e sviluppi metodologici tenutosi a Milano nel 2013.
How different emission estimation methods can affect final result? The case of milk production
M. Guerci;L. Bava;A. Sandrucci;M. Zucali;A. Tamburini
2013
Abstract
The livestock sector heavily contributes to anthropogenic greenhouse gas emissions especially from enteric fermentation of ruminants, manure management and crop production, but it is also responsible of a large share of ammonia volatilization and nitrate leaching. Life Cycle Assessment (LCA) is a powerful tool to analyze the environmental impact of a product and identify process hotspots. However it is a very complex, time and labor intensive methodology and its results are often affected by different sources of uncertainty. In some contexts a simplified approach could be convenient, provided the accuracy of the results is not compromised. The aim of this study was to compare environmental impacts of milk production obtained from a life cycle analysis using different methodologies for emission estimation at farm level. A group of 29 dairy farms was involved in the study, data were collected through personal interviews to the farmers. On-farm emissions were estimated with a detailed approach using Tier 2 methods from IPCC (2006a,b) and EAA (2009a,b) and with a simplified approach using Tier 1 method from IPCC (2006a,b); the global impact was evaluated with the support of SimaPro software. In general the simplified approach underestimated global warming potential compared to detailed one but slightly overestimated acidification potential; there was no significant difference in terms of eutrophication potential. Overall, even if the simplified approach used fixed values of methane and nitrogen excretion while the detailed approach was based on more specific evaluations, the two methods did not greatly differ in the estimation of total amount of methane and nitrogen lost by the animals. As a consequence very similar impact values were obtained with the two approaches. The simplified approach seems to be a convenient method when a large number of production units are involved in the evaluation. On the contrary the detailed approach is more appropriate for research purposes to identify the different emission sources and their contribution to the impact.
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