Evolution of properties of macadamia husk throughout gasification: Hints for a zero-waste energy production system

In-depth information about the transformation of biomass during gasification is the key to the sustainable development of this technology. This study elucidated the evolution of physico-chemical properties of macadamia husk throughout relevant industrial gasification conditions. The technical characteristics combined with high conversion rate highlighted the suitability of this feedstock for gasification. A stable syngas flow rate with high concentrations of CO and H2, reaching a lower heating value of 13.8 MJ m−3 on average was obtained. Relatively porous chars with a majority of micro-mesopores were observed throughout the conversion, which suggests the potential to use the residues after gasification as cheap and efficient adsorbents. In addition, multiple carboxyl and hydroxyl functional groups were present on the char surface. Moreover, a high K content was detected (ranging from 85 mg g−1 for pyrolyzed MH char to 746 mg g−1 for MH gasified char at the conversion rate of 85%) and evenly distributed on the char surface. Such results consolidated the idea of combining the production of energy and cheap bio-fertilizers using the gasification of macadamia husk. The resulting database offered interesting hints for the development of zero-waste energy production systems with biomass gasification.