Today, fossil fuels supply about 80% of the worldwide energy consumption, and about 58% of this amount belongs to traortation sector. On the other hand, the limited resources of these fuels and the devastating impact they have on the environment through greenhouse gas emissions, are among the problems facing the world in terms of energy supply. Biofuels are a promising alternative to current energy sources because of the diversity and availability of raw materials, the reduction of greenhouse gas emissions, and their potential to reduce fuel production costs. A biorefinery is a broad concept in which biological biomass as a feedstock of processes is transformed into a diverse range of valuable products. In this study, olive wastes were used as feedstock for a biorefinery plant. The maximum amount of 366.4 L/1 ton substrate gasoline equivalent was obtained in this plant. A pretreatment step was applied to isolate lignin and hemicellulose and facilitate enzyme access. The effect of phosphoric acid, organic solvent with and without acid catalyst and hot water pretreatment were evaluated on bioethanol and biogas production. phosphoric acid caused a three-fold improvement in biomethan production from leaves and deoiled olive stones, increased their production to 208.9, 153.6 ml/g- VS, respectively, while pretreatments had negative effect on methane production from olive stones and pulps where the untreated samples produced higher amount of biomethan (203.9, 191.1 ml/g-VS, respectively).The effect of phenolic extractives on methane and bioethanol production were also investigated. An extraction step can increase methane production from olive leaves up to 285.2 ml/g-VS(three-fold enhancement), bioethanol production was also improved by phenolic removal (50% rised). Organic solvent with addition of sulfuric acid as a catalyst, was able to improve ethanol production from olive leaves and stones up to 8.4, 9.2 g/l, respectively, and hot water pretreatment with 8.8 g/l product, was recognized as the best way to produce ethanol from the olive pulp. The residual oil in the olive pulps and stones were extracted by a soxhlet extractor and n-hexane as solvent. The free fatty acid (FFA) contents of extracted oils were measured before biodiesel production. Since oils had low level of FFA (1.5%) it was directly subjected to alkaline transesterification process. The maximum yield of olive biodiesel obtained at 65?, methanol to oil ratio of 0.6 and 120 min, was 84.2%.
