Assessment of biochar developed via torrefaction of food waste as feedstock for steam gasification to produce hydrogen rich gas

Abstract

AbstractIn this study, the torrefaction of food waste was carried out using a thermogravimetric analyzer (TGA) to produce biochar and assess its suitability as feedstock for steam gasification. Torrefaction was conducted at temperature from 230 to 290 °C and the heating rate from 10 °C/min to 30 °C/min. Subsequently, the detailed characterization was conducted using proximate, elemental, lignocellulosic, nutrient analysis, and TGA analysis. The proximate and elemental analysis showed that biochar had the highest fixed and elemental carbon at the highest temperature (290 °C) and lowest heating rate (10 °C/min). Similarly, TGA indicated that increase in temperature increased the mass loss, however, increase in heating rate did not yield much change in mass loss. Additionally, lignocellulosic and nutrient analysis showed that lignin fraction increased (up to 80%) with increases in severity of the torrefaction due to significant decomposition of hemicellulose, cellulose, starch, proteins, and lipids. Thereafter, the kinetic parameters (activation energy, pre-exponential factor) of torrefaction of food waste were determined using the two-step decomposition model which showed a good fit with experimental data. Finally, the biochar developed was used for energy production using steam gasification which produced syngas with maximum yield of 3.75 m3/Kg and having hydrogen fraction of around 65% at the optimal conditions (temperature: 290 °C, heating rate: 10 °C/min). Graphical Abstract