Sustainable Plasma Gasification Treatment of Plastic Waste: Evaluating Environmental, Economic, and Strategic Dimensions

The conversion of waste to energy is an essential process in the Middle East, especially in Saudi Arabia, where it plays a crucial role in waste management. The annual analysis of the decomposition hazards of the landfills in the city of Makkah showed that they ranged from 168,000 Mg in 1994 to 297,000 Mg in 2022. The emission costs of pollution ranged from 4 million in 1994 to 7 million in 2022. The number of gas emissions of plastic waste accumulating in the analyzed landfill has increased from 128,000 Mg in 1994 to 227,000 Mg in 2022. The thermal plasmas used were produced by air plasma torches, which are an essential part of plasma reactors. The operational characteristics of air plasma torches were investigated at a flow rate of 10–30 g/s, including current–voltage characteristics, applied power, applied flow rate, average temperatures of the exiting plasma jet ranging from 15,000 to 19,000 K, average velocity of the exiting plasma jet (1677.3–2763.2) m/s, wavelength of the emitted radiation ranging from 153 to 193 nm, and the corresponding beam lengths ranging from 400 to 450 mm. The proposed plasma gasification is the greenest method for processing plastic waste in the light of ecological, economic, and strategic visions with an amount of recovered pyrolysis oil in the year 2022 of 3.17 × 105 tons with an equivalent energy of 12.55 × 109 MJ, with an output efficiency value equal to 81%. A roadmap for the economic and environmental visions was introduced, where the economic return on investment (ROR%) was 80%, the payback period (PBP) was 1.2 years, and the gross profit reached 129%.