Poultry litter utilization for waste-to-wealth: Valorization process simulation and comparative analysis based on thermodynamic and techno-economic assessment

The utilization of poultry litter for converting poultry litter into energy or value-added products has great potential for energy saving and environmental protection. In this study, four integrated processes for treating poultry litter and obtaining high-value-added products have been studied: supercritical water gasification for hydrogen and electricity (SCWG-HE), supercritical water gasification for electricity (SCWG-E), steam gasification for electricity (SG-E) and steam gasification for hydrogen (SG-H). Thermodynamic and tech-economic assessments have been adopted to analyze the treatment alternatives comprehensively. The following findings have been obtained: (1) The energy/exergy efficiency of process has a positive correlation with the heat value of syngas; (2) The highest energy/exergy efficiency (57 % / 72 %) is accompanied by the highest H-2 yield (50.87 mol.kg(-1)) under the operation conditions; (3) For each integrated process, the most exergy loss link occurs at the gasification unit and Rankine cycle; (4) CO2 separators in integrated processes contribute little to energy-saving, accompanied with high investment (more than 27.5 % in SCWG-E, even until 74.2 % in SG-E). In conclusion, the findings of the study revealed the potential of multi-energy utilization for poultry litter in a farm and suggested that SG-H might be a better alternative with the highest efficiency and lowest equipment cost.