Technoeconomic feasibility of a waste-to-energy (WtE) polygeneration system implementing circular carbon strategies: A case study for Spain

Waste-to-energy (WtE) polygeneration systems present an integrated solution for addressing waste management challenges, while in parallel producing energy, fuels, and freshwater. In this paper, a new WtE system based on wood residues is proposed. The system consists of an integrated biomass gasification combined cycle including carbon capture, hydrogen separation, methanol synthesis, multi-stage flash desalination, and domestic heating systems. Hydrogen can be used directly as a fuel or an intermediate product. The captured carbon is utilized for methanol production, which enhances system flexibility and overall performance. A technoeconomic analysis is carried out using total revenue requirement (TRR) method to assess the feasibility of the system. In addition, a parametric study is conducted, evaluating the system from energy and exergy perspectives based on key indicators. Besides, a genetic optimization algorithm is employed to determine the optimum for various cases to maximize power generation, enhance efficiencies, and promote sustainability. The energy and exergy efficiencies for the base case are 55.22 % and 37.92 %, which are improved up to 67.58 % and 46.64 % after exergy optimization. The LCOE and LCOH, for the benchmark system, obtained as 0.08 $/kWh and 0.04 $/kWh, while the LCOH₂, LCOM, and LCOW are 2.43 $/kg, 0.33 $/kg, and 0.12 $/m³, respectively.