Developing an off-grid biomass gasification cogeneration system for Moroccan olive oil mills: Simulation, experimental validation, and 3E analysis

Applying biomass gasification in combined heat and power systems (BCHPs) at olive oil mills is a sustainable energy solution, which allows effectively managing waste, mitigating greenhouse gas emissions, and optimizing investments by reducing biomass transportation costs. Morocco, a major global olive oil producer, has abundant olive groves and mills generating substantial amounts of waste. However, limited research exists on utilizing olive oil waste for BCHPs in Moroccan mills. This article proposes the construction of a BCHP in DARA mill, Morocco, including studying residues from olive oil production, simulating the BCHP, validating the gasification process through experiments, conducting energy, exergy and exergoeconomic analyses, and performing the parametric study on system performance. In the experimental data, the equivalence ratio for olive cake and olive pruning was obtained at 0.3 and 0.32, which agrees well with the simulated model by 0.31 and 0.315. The energy analysis revealed that 30% of input energy is converted to useful energy, while 70% is wasted, resulting in a 42% efficiency. From the exergy analysis, it was found that only 18% of the entered exergy is utilized as useful exergy, while 68% is destroyed and 12% is lost, resulting in 19% efficiency Investment expenses contribute to 87% of system costs, with cost of exergy destruction accounting for the remaining 13%. The engine, gasifier, and cleaning unit incur the highest exergy destruction and associated costs. Increasing both the air-fuel ratio (from 1.7 to 2) and water-fuel ratio (from 0.001 to 0.25) simultaneously leads to a 21% decrease in system exergy efficiency, a 3% increase in investment costs, and a 10% increase in costs related to exergy destruction.