Global Warming Potential Analysis of Olive Pomace Processing

Abstract

The olive pomace is a by-product of olive oil production, obtained after milling operations. The milling process can be done by traditional pressing operations, or through centrifugation (that occurred in two or three phases). Depending on the used process and on the number of phases, the olive pomace has a different moisture content and requires different amounts of energy to be dried. On completion of this stage, the residual oil (up to 4 % by weight) is extracted through a mixture of steam and hexane. The drying and the extraction phase are both obtained using hot air and superheated steam produced in a boiler, which uses exhausted pomace (oil-free pomace) at the end of the process. The aim of this study was the analysis of the CO2 emissions and the evaluation of the Global Warming Potential (GWP) related to the production of 1 kg of pomace oil (widely used by food industry) and 1 kg of exhausted pomace (used as biofuel). The analysis was performed considering the industrial stages (gate-to- gate approach), varying the type of olive pomace, which depends on the specific milling process. Process data were collected from the chosen industrial site and the life cycle inventory was performed in according to the reference standard ISO 14040-14044.