The explosion of plastic waste generation, approaching 400 million tons per year, has created a worldwide environmental crisis that conventional waste management systems cannot handle. This problem can be solved through gasification, which converts nonrecyclable plastics to syngas with potential applications in electricity generation and synthetic fuel production. This study investigates whether syngas production from plastic waste by gasification is environmentally and economically feasible. Environmental impacts were assessed through a life cycle assessment framework using a life cycle impact assessment approach, ReCiPe 2016, with 10 midpoint/endpoint categories. Midpoint results of the baseline scenario with grid-mix electricity revealed climate change (GWP) of 775 kg CO₂ equivalent and fossil depletion potential (FDP) of 311 kg oil equivalent per ton of plastic waste. Meanwhile, a solar scenario showed GWP as 435 kg CO₂ equivalent and FDP as 166 kg oil equivalent per ton of plastic waste. Switching to solar energy cut GWP 44% and FDP 47%, respectively. However, the tradeoffs were higher human toxicity potential (HTP) and marine ecotoxicity potential (METP) due to upstream material extraction of renewable systems, respectively. Among environmental performance drivers, electricity inputs and operating materials were identified through sensitivity and uncertainty analyses. Syngas production from a plant of 50 tons per day can yield electricity sales revenue of USD 4.79 million, excluding USD 4.05 million in operational expenditures. Financial indicators like a 2.06-year payback period, USD 5.32 million net present value over a 20-year project life, and 38.2% internal rate of return indicate the profitability of the system. An external cost analysis showed emissions-related costs of USD 26.43 per ton of plastic waste processed, dominated by CO₂ and NO_x emissions. Despite these costs, the avoided impacts of less landfilling/incineration and electricity generation support gasification. Gasification should be promoted as a subsidy and incentive by policymakers for wider adoption and integration into municipal waste management systems. Findings show it can be adapted to global sustainability goals and circular economy principles while delivering strong economic returns. The study findings also contribute to several Sustainable Development Goals (SDGs), for instance, SDG 7 by promoting clean energy technologies, SDG 12 by implementing circular economy, and SDG 13 by reducing greenhouse gas (GHG) emissions.

This study aims to evaluate the environmental and economic performance of biodiesel production from mixed vegetable oil waste using the life cycle assessment (LCA) model. Due to its huge potential, Pakistan is taken as a case study. It produces 468,842 tons of vegetable oil waste annually. As no biodiesel production plant exists to process it, the environmental performance of biodiesel prototypes has not been investigated. Therefore, the current study is conducted to support the design of a plant to produce biodiesel from mixed oil waste. An attributional LCA was conducted using ReCiPe (H) and found that 400 kg of biodiesel can be produced from 1 t of mixed oil waste. The results, based on a functional unit of 1 ton, showed that biodiesel production from mixed vegetable oil waste is more eco-friendly than the existing landfilling practices with a global warming potential of 1.36 × 10⁻⁴ kg CO₂ eq, human toxicity of 5.31 kg 1.4 DB eq, ozone depletion potential of 0.00271 kg CFC-11 eq, eutrophication potential of 0.0118 kg P eq, acidification potential of 123 kg SO₂ eq, and photochemical ozone formation of 51.4 kg NO_x eq. Scenario modelling was conducted using electricity from photovoltaic solar cells, which decrease fine particulate matter formation from 44.5 to 0.725 kg PM₂.₅ eq, instead of using electricity from a grid to the plant. Hotspot identification was carried out to highlight the effects of individual impact categories. An economic analysis showed that 638,839 USD/year revenue would be generated. Generating energy from discarded vegetable oils through biodiesel production presents a sustainable and economically viable approach. This process benefits the environment and contributes to cost savings by reducing waste disposal in landfills. Furthermore, it aligns with the principles of a circular economy, in which resources are reused and recycled. It also supports the pursuit of the United Nations’ Sustainable Development Goals (SDGs), particularly SDG-7, which focuses on affordable and clean energy, and SDG-12, which emphasizes responsible consumption and production.