Energy- exergy-economics-life cycle environmental impact coupling evaluation of coal tar residue supercritical water gasification for hydrogen and electricity co-generation system

In response to the pollution control and resource utilization challenges of coal tar residue (CTR) as a hazardous waste, this paper constructs a combined system of supercritical water gasification (SCWG) for hydrogen production and electricity generation. A coupled evaluation of “energy-exergy-economics-life cycle environmental impact” was conducted using life cycle assessment (LCA) and techno-economic analysis (TEA), systematically investigating the resource consumption, environmental impacts, and economic feasibility of the integrated system throughout its entire life cycle. The results indicate that gasification temperature and the proportion of preheated water are the primary factors influencing system efficiency and environmental impacts. The maximum energy efficiency of the system is 44.53%, and the maximum exergy efficiency is 37.97%. After sequestering the carbon dioxide generated from the SCWG process, the GWP100a can be reduced to 10.19 kg CO 2 eq/kg H 2 . Raw material subsidies/prices, hydrogen selling prices, catalyst prices, oxygen prices, and electricity prices are the key factors affecting the economics of the system. Based on the current market environment, the hydrogen cost is approximately 15 Chinese Yuan (CNY)/kg, the electricity generation cost is about 0.4 CNY/kWh, the dynamic payback period (DPBP) is around 1.6 years, and the net present value (NPV) is 11.36 × 10 8 CNY.