Thermodynamic and techno-economic analysis of hydrogen production from food waste by torrefaction integrated with steam gasification

Abstract

Although torrefaction has been proven as a promising pretreatment method that can improve the gasification performance of food waste, the effect of torrefaction on the energy and exergy distribution and economic feasibility of the whole hydrogen production system is still unknown. In this study, a process of hydrogen production from food waste (5 tonnes/h) by torrefaction integrated with steam gasification (TG) was simulated, focusing on the comprehensive evaluation between TG and direct gasification (DG) in view of the thermodynamic, techno-economic, and economic sensitivity analysis. The thermodynamic results showed that the energy efficiency and exergy efficiency of TG could reach 58.9 % and 59.6 %, respectively, which was higher than that of DG (56.8 % and 57.2 %). The techno-economic analysis results indicated that TG had a shorter payback period of 5.7 years, lower minimum hydrogen selling price (MHSP) of US$ 2.48/kg, larger internal rate of return (NPV) of 25.0 %, and higher net present value of US$ 19.8 million, which displayed a higher commercial potential than DG (7.2 years, US$ 2.90/kg, US$ 13.7 million, and 20.4 %). The H2 selling price and discounted rate were the most sensitive parameters affecting NPV and MHSP, respectively. During market turbulence, the NPV of TG changed less and had more robust adaptability compared to DG, whereas the opposite tendency was found for MHSP. When the scale expanded to 400 dry tonnes/d, the MHSP of DG and TG can further reduce by 45.8 % and 50.3 %, respectively. The results of this work provide fundamental guidance for the commercialization of large-scale H2 production from food waste via TG.