Spent coffee grounds and wood co-firing: Fuel preparation, properties, thermal decomposition, and emissions

journal article in Web of Science

en

Spent coffee grounds (SCG) is the byproduct of coffee preparation. With coffee being one of world's most traded commodities, the question of SCG utilization is naturally raised. Among the proposed and tried methods, direct co-firing with wood or other materials is still perceived as the method most local SCG producers could easily incorporate into a waste-to-energy supply chain for circular economy. This study thus delved into assessing the technical feasibility of SCG and wood co-firing. As part of the research, a thorough investigation into fuel properties, pelleting, boiler performance and emissions was conducted. A possible antagonistic behavior between SCG and wood was observed during thermogravimetric analysis and the subsequent emission tests. The thermogravimetric analysis also showed negligible difference in thermal decomposition of SCG from different places of origin. The mechanical durability of wood/SCG pellets was found to be significantly reduced by SCG, and the pellets would not meet the EN ISO 17255 requirements in any of the tested ratios. Compared to wood, the NO emissions were significantly higher when firing the SCG-containing pellets. However, no direct correlation was found between the NO concentrations and the amount of SCG in the blends, thus hinting at other factors affecting the NO formation.

Spent coffee grounds (SCG) is the byproduct of coffee preparation. With coffee being one of world's most traded commodities, the question of SCG utilization is naturally raised. Among the proposed and tried methods, direct co-firing with wood or other materials is still perceived as the method most local SCG producers could easily incorporate into a waste-to-energy supply chain for circular economy. This study thus delved into assessing the technical feasibility of SCG and wood co-firing. As part of the research, a thorough investigation into fuel properties, pelleting, boiler performance and emissions was conducted. A possible antagonistic behavior between SCG and wood was observed during thermogravimetric analysis and the subsequent emission tests. The thermogravimetric analysis also showed negligible difference in thermal decomposition of SCG from different places of origin. The mechanical durability of wood/SCG pellets was found to be significantly reduced by SCG, and the pellets would not meet the EN ISO 17255 requirements in any of the tested ratios. Compared to wood, the NO emissions were significantly higher when firing the SCG-containing pellets. However, no direct correlation was found between the NO concentrations and the amount of SCG in the blends, thus hinting at other factors affecting the NO formation.

Spent coffee grounds, Pelleting, Co-firing, Emissions, TGA

20.06.2022

Elsevier

0960-1481

193

červen

464–474

10