GHG Emissions of the Extra Virgin Olive oil Production

This study aims to calculate the greenhouse gas emissions (indicated as kg of CO2eq) related to the production of one liter of extra virgin olive oil. In this analysis we considered three olive-growing models: the traditional “Secular olive grove,” the common “High Density” (HDO), and the innovative “Super High Density” (SHDO) olive orchards. The latter two models are distinguished by the higher number of olive trees per hectare and by the full mechanization of the agricultural practices. Four different olive oil production technologies were compared: the pitted system, the two-phase system, the three-phase system, and the pressing system. All combinations of the agricultural and the processing phases were studied. Data about the agricultural practices and the olive oil production systems were collected from farms and olive oil industries in the Apulia region. As for the data not available from these farms and industries, the databases Ecoinvent v 2.2 and Pe-international were searched, and the results elaborated using the software GaBi 6. Data were collected about pruning residues that was grinded and buried, but not about any that was burned in the field, since this practice was forbidden by law. The kg of CO2eq produced per liter of extra virgin olive oil ranges between 1.091, in the case of the combination of SHDO and the three-phase system, and 1.252, for the combination of HDO and the pitted system. The analysis shows that the olive production phase accounts for over 94% of the overall greenhouse gas emissions (kg di CO2eq) related to the production of extra virgin olive oil. This is principally due to the use of nitrogen fertilizers (from 0.724 kg of CO2eq per liter for the SHDO to 1.047 for the secular olive orchard), and irrigation for HDO and SHDO (0.184 kg of CO2eq per liter). In addition, in the case of SHDO the mechanized harvesting involves 0.152 kg of CO2eq per liter. The comparison among the olive-growing models highlights the finding that the HDO entails less emission of CO2eq. This model, in fact, requires less resources than SHDO, while allowing a similar yield per hectare. The only advantage of SHDO is economic, because the full mechanization entails lower costs. The greenhouse gas emissions related to the olive oil production systems are principally due to the electricity used by the machinery. Since the pressure system presents to the least "energy intensive" and in the most "labor intensive" technology, this involves the lower greenhouse gas emissions. The pitted system, that foresee the partial elimination of fragments of olive pit yields a higher percentage of olive oil. For this reason, if we consider the different combinations among olive-growing models and olive oil production systems, the olive production by HDO combined with the pitted system is the most sustainable.