Hydrogen-based synthetic fuel production from excavated waste: life cycle techno-environmental-economic choices of technical routes and targeted products

Organic content in the excavated waste (EW) can be a sustainable feedstock source for hydrogen-based fuel (HBF) production, which includes H2, NH3, methanol (MeOH), and liquefied natural gas (LNG). In this study, various EW-to-HBF (EWtHBF) systems with different technical routes are proposed, and based on the Aspen Plus simulation results, exergy analysis, life cycle assessment (LCA), and life cycle cost (LCC) are conducted to evaluate the techno-environmental-economic (3E) performance. For reforming routes, the traditional water gas shift (WGS) integrated with acid gas removal (AGR) and new-proposed sorption-enhanced water gas shift (SEWGS) are compared, while for feed gas ratio adjustment method, end-stream remixing and midstream bypassing are discussed. The results showed that applying SEWGS and midstream bypassing adjustment method can comprehensively improve the 3E performances in all schemes. The optimal ηex for H2, NH3, MeOH and LNG production is respectively ∼59 %, ∼55 %, ∼62 %, and ∼61 %. The targeted production of H2, LNG, and MeOH is the respective best choice from the perspectives of economic-take-all, environmental-take-all, and economic-environmental-parallel. Sensitivity analysis shows that the HBF selling prices are the most influential factor. Economically speaking, if the H2 selling subsidy is cancelled, the production of NH3 and MeOH can be suitable substitutions.