An integrated gasification plant for electric power generation from wet biomass: toward a sustainable production in the olive oil industry

This research work proposes an integrated gasification plant for simultaneous generation of renewable electricity and drying of olive pomace, a thick sludge with a moisture content close to 60-70% (wet basis), which constitutes by far the most abundant by-product in the Spanish olive oil industry. Due to its massive rate of production and increasing associated transportation costs, olive pomace management currently represents a substantial expense for oil mills. The integrated gasification plant, which can be installed directly at oil mills, consists of a pelletizer, a downdraft gasifier under autothermal operation fueled with dried olive pomace pellets, a producer gas cooling and cleaning unit and a microturbine as power generation unit. The wet olive pomace continuously produced in oil mills is eventually dried in a co-current flow rotary drum dryer with the hot exhaust gases leaving the microturbine at temperatures close to 300 degrees C, allowing a self-sufficient operation of the integrated gasification plant. The integrated gasification plant was modeled using Aspen Plus (R) process simulator. The developed model was validated against experimental and simulation results of relevant works. Under optimum operating conditions, the electrical efficiency of the proposed plant is 18.8%, while the additional drying stage allows achieving an overall efficiency of 51.0%. Electricity consumption by the pelletizer and ancillary equipment represents 10-20% of the net electric power generation from the microturbine. However, since the integrated gasification plant is fueled with an inexpensive by-product of olive oil production that is massively produced on-site, the plant performance parameters are remarkably satisfactory.