Techno-economic analysis of sewage sludge supercritical water gasification for hydrogen and electricity co-generation system

The harmless and resourceful sewage sludge (SS) treatment has attracted significant attention. In this paper, a detailed techno-economic analysis of the SS supercritical water gasification (SCWG) process was carried out to investigate its economic feasibility, and four scenarios with different operating conditions of the constructed poly-generation system were investigated. The highest economic benefits (ROI of 24.94 %, PP of 3.78 years, and NPV of 315.32 million CNY) could be realized at a reaction temperature of 750 °C and a system SS treatment capacity of 20 t/h. Under this condition, the fixed capital cost (FCC) was 85.20 million CNY and the levelized cost of hydrogen (LCOH) was 17.07 CNY/kg. Further sensitivity analyses showed that NPV and ROI grew and PP shortened as the H2 selling price increased. Natural gas price, SS subsidy, electricity price, and energy consumption of the CO2 separation unit were important factors affecting LCOH. Hydrogen production from SCWG utilizing SS as feedstock is an environmentally friendly technology and more economical than other hydrogen production processes. © 2024 Elsevier Ltd