Quality of Pelleted Olive Cake for Energy Generation

Olive cake is by-product of olive oil production. This material cannot be stored in original condition for a long time because it has high water content and relatively high portion of oil that causes rapid deterioration. Thus it is necessary to investigate possible methods of remediation of such by-product, where utilization for energy generation presents a useful option. Several studies have been conducted on energy generation from olive cake, however not one that includes pelleting as a pre-treatment. Therefore, the aim of this paper was to determine the chemical composition of different cultivars of olive cake, to produce pellets, and determine their basic quality parameters. The pellets obtained from olive cake had mainly satisfactory results regarding their quality in comparison to standards for fuel pellets. It should be kept in mind that these standards are manly for wood pellets, and therefore some lower criteria could be applied for olive cake and such biomass. The highest amount of residual oil and the lowest amount of protein was found in cultivar ‘Bu a’ and produced pellets had the smallest abrasion index (8.15%). Other cultivars had lower oil and higher protein content, and abrasion index higher than 10%. For these cultivars preparation of material (conditioning and/or binder adding) prior to pelleting is necessary. Higher heating value (HHV) and lower heating value (LHV) were not significantly influenced by different chemical composition of cultivars, thus attention should be paid on their influence on pelleting process.