Management of Olive Grove Pruning and Solid Waste from Olive Oil Extraction Via Thermochemical Processes

Abstract

Olive oil production is a significant economic activity in the Mediterranean basin and a considerable employment source, while the environmental pressures associated with the olive tree farming and olive oil extraction are remarkable and increasingly important. Olive farming and olive oil processing are generating large quantities of solid and liquid wastes, the disposal of which are still considered as a major problem for the farmers and the mill operators. The commonly applied management practice of combustion is not fully in line with sustainability criteria. Taking into consideration that the average size of olive groves and olive mills in the Mediterranean countries is relatively small, the management of olive farming wastes via thermochemical routes could develop an energy self-maintained decentralized system that contributes to the conservation of natural resources and is in line with the principles of ecology and sustainable agriculture. In this context, this work investigates pyrolysis and gasification as potential scenarios for waste management in the case of an olive grove of 10 hectares. The results have shown that the produced electricity, in both cases, is not only enough to cover the energy required for milling operations but is also producing a surplus that can be supplied to the grid and sold, thus providing an extra income to the farmer, boosting the economic viability of all the process. Pyrolysis, in addition, has the advantage of providing a soil amendment (bio-char), thus enhancing soil quality and carbon sequestration into the soil.