Annually, the olive oil industry generates a significant amount of by-products, such as olive pomace, olive husks, tree prunings, leaves, pits, and branches. Therefore, the recovery of these residues has become a major challenge in Mediterranean countries. The utilization of olive industry residues has received much attention in recent years, especially for energy purposes. Accordingly, this primary experimental study aims at investigating the potential of olive biomass waste for energy recovery in terms of synthesis gas (or syngas) production using the thermal arc plasma gasification method. The olive charcoal made from the exhausted olive solid waste (olive pomace) was chosen as a reference material for primary experiments with known composition from the performed proximate and ultimate analysis. The experiments were carried out at various operational parameters: raw biomass and water vapour flow rates and the plasma generator power. The producer gas involved principally CO, H 2 , and CO 2 with the highest concentrations of 41.17%, 13.06%, and 13.48%, respectively. The produced synthesis gas has a lower heating value of 6.09 MJ/nm 3 at the H 2 O/C ratio of 3.15 and the plasma torch had a power of 52.2 kW.

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Glycerol, considered as a waste feedstock resulting from biodiesel production, has received much attention in recent years due to its properties, which offer to recover energy. The aim of this study was to investigate the use of a thermal water vapor plasma for waste (crude) glycerol conversion to synthesis gas, or syngas (H + CO). In parallel of crude glycerol, a pure glycerol (99.5%) was used as a reference material in order to compare the concentrations of the formed product gas. A direct current (DC) arc plasma torch stabilized by a mixture of argon/water vapor was utilized for the effective glycerol conversion to hydrogen-rich synthesis gas. It was found that after waste glycerol treatment, the main reaction products were gases with corresponding concentrations of H 50.7%, CO 23.53%, CO 11.45%, and CH 3.82%, and traces of CH and CH, which concentrations were below 0.5%. The comparable concentrations of the formed gas products were obtained after pure glycerol conversion-H 46.4%, CO 26.25%, CO 11.3%, and CH 4.7%. The use of thermal water vapor plasma producing synthesis gas is an effective method to recover energy from both crude and pure glycerol. The performance of the glycerol conversion system was defined in terms of the produced gas yield, the carbon conversion efficiency, the cold gas efficiency, and the specific energy requirements.

The depletion and usage of fossil fuels causes environmental issues and alternative fuels and technologies are urgently required. Therefore, thermal arc water vapor plasma for a fast and robust waste/biomass treatment is an alternative to the syngas method. Waste cooking oil (WCO) can be used as an alternative potential feedstock for syngas production. The goal of this experimental study was to conduct experiments gasifying waste cooking oil to syngas. The WCO was characterized in order to examine its properties and composition in the conversion process. The WCO gasification system was quantified in terms of the produced gas concentration, the H2/CO ratio, the lower heating value (LHV), the carbon conversion efficiency (CCE), the energy conversion efficiency (ECE), the specific energy requirements (SER), and the tar content in the syngas. The best gasification process efficiency was obtained at the gasifying agent-to-feedstock (S/WCO) ratio of 2.33. At this ratio, the highest concentration of hydrogen and carbon monoxide, the H2/CO ratio, the LHV, the CCE, the ECE, the SER, and the tar content were 47.9%, 22.42%, 2.14, 12.7 MJ/Nm3, 41.3% 85.42%, 196.2 kJ/mol (or 1.8 kWh/kg), and 0.18 g/Nm3, respectively. As a general conclusion, it can be stated that the thermal arc-plasma method used in this study can be effectively used for waste cooking oil gasification to high quality syngas with a rather low content of tars.