Suitability of Jatropha seed shells as fuel for small-scale combustion units

Increasing use of deshelled Jatropha seeds will result in a rising amount of seed shells as processing residues. Therefore, the aim of this study was to determine the physical and chemical properties of Jatropha seed shell and ashes as well as the development and testing of a robust and functional combustion unit for the thermal use those residual materials.Analyses of physical and chemical properties of Jatropha seed shell and ash were done according to standard methods and compared to rice husk and pinewood.The combustion of Jatropha seed shell for heat generation is well accomplishable without previous processing of seed shell such as pelletizing or briquetting. Thermal power was between 11.1 kW and 36.7 kW corresponding to a feeding rate of Jatropha seed shells between 2.9 kg/h and 9.0 kg/h with furnace efficiency of 87% and 91%.Ash melting and slag creation on the grate as well as clogging of the combustion air supply holes, by sintering ash on the grate was not observed. The concentrations of CO in the flue gas was 2.8 ± 0.8 g/m3 and therefore lower than threshold value with 4 g/m3 for CO emission for combustion of wood according to German legal requirements for combustion units up to 50 kW.Coarse ashes are suitable for application as fertilizer in agriculture due to their high contents of the major plant nutrients. However, attention has to be paid to the content of heavy metals, which has to be reduced by suitable methods.

► Physical and chemical properties of Jatropha seed shell and ashes.
► Combustion of Jatropha seed shell without previous processing of seed shell.
► Information about combustion behavior of Jatropha seed shell in small-scale combustion units.