Thermochemical Conversion of Olive Oil Industry Waste: Circular Economy through Energy Recovery

Leonel J R Nunes,Letícia C R Sá,Liliana M E F Loureiro,Hugo F.C Silva

doi:10.3390/recycling5020012

Leonel J R Nunes, Letícia C R Sá + Show 2 more

Open Access

https://doi.org/10.3390/recycling5020012

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Abstract

The demand for new sources of energy is one of the main quests for humans. At the same time, there is a growing need to eliminate or recover a set of industrial or agroforestry waste sources. In this context, several options may be of interest, especially given the amounts produced and environmental impacts caused. Olive pomace can be considered one of these options. Portugal, as one of the most prominent producers of olive oil, therefore, also faces the problem of dealing with the waste of the olive oil industry. Olive pomace energy recovery is a subject referenced in many different studies and reports since long ago. However, traditional forms of recovery, such as direct combustion, did not prove to be the best solution, mainly due to its fuel properties and other characteristics, which cause difficulties in its storage and transportation as well. Torrefaction and pyrolysis can contribute to a volume reduction, optimizing storage and transportation. In this preliminary study, were carried out torrefaction and pyrolysis tests on olive pomace samples, processed at 300 °C, 400 °C, and 500 °C, followed by laboratory characterization of the materials. It was verified an improvement in the energy content of the materials, demonstrating that there is potential for the use of these thermochemical conversion technologies for the energy recovery of olive pomace.

Highlights

Olive oil production is an activity of vital economic importance in Mediterranean countries [1].Portugal is a reference in modern olive growing, and is expected during decade to be the third largest producer of olive oil in the world and the seventh largest in terms of occupied area [2]
This work aims to evaluate the potential of using olive pomace as a renewable energy source in the perspective of circular economy, where waste is reused and incorporated into a new production cycle
Several analyses were carried out to characterize the evolution of the olive pomace properties resulting from the torrefaction and pyrolysis processes

Summary

Introduction

Portugal is a reference in modern olive growing, and is expected during decade to be the third largest producer of olive oil in the world and the seventh largest in terms of occupied area [2]. This growth is sustained by the evolution in the country and, in particular, in Alentejo, Southern Portugal, with the contribution of Alqueva dam that provided the irrigation for intensive crops [3]. Olives Information System-https://www.gpp.pt—indicated a 30% drop in oil production compared to the previous campaign. As the ninth producer in the world, Portugal has 361 thousand hectares of olive groves, and 135 thousand tons of oil extracted

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