Study of a downdraft gasifier and gas engine fueled with olive oil industry wastes

Currently, there are around 2000 operative olive oil mills in Spain. Crushed olive pits and rests of small branches and leaves are produced during the olive oil extraction process. This biomass source could be a feasible option in gasification technology applied to distribute generation. This paper is focused on the modeling of a small-scale plant based on a downdraft gasifier and a gas engine connected to the grid. The producer gas from the gasification process reaches a calorific value of 5.1 MJ kg−1 (for crushed olive pits) and 3.7 MJ kg−1 (for small branches and leaves). The system provides 70 kWe and 110 kWth with a biomass consumption of 105 kg h−1. Cycle-Tempo® and Matlab®/Simulink® have been used to simulate and calculate the optimum operating parameters of the plant. Electric efficiency of 14%, overall efficiency of 36% and high gasification efficiencies can be achievable with such a system.