This paper promotes awareness of the circular economy as a superior waste disposal system alternative. The novelty of this study is to model cleaner energy generation from the gasification of polyethene terephthalate (PET) waste accompanied by a detailed analysis on the economic feasibility. In the approximate analysis of PET, the percentage values for Ash and hydrogen were low (0 and 4.21, respectively). This parameter significantly impacted the Ash and hydrogen contents of the output gas, as it directly influenced the PET feedstock to a more excellent heating value (23.34 MJ/kg) and lower heating value (10.63 MJ/kg). Temperature and pressure are treated as free variables throughout each block during the gasification procedures. A sensitivity study revealed that the PET moisture content has no significant effect on the product composition. The economic analysis indicated that the gasification process could be economically viable. The economic analysis of the process considered the comprehensive evaluation of the plant’s financial aspects. The economic evaluation indicated that the facility would reach the break-even point by the end of its third year of operation, demonstrating its economic viability, with an NPV of £77,574,506.37 and an ROI of 40.1% for the suggested 25-year operational period of the facility.