Comparison of waste plastic fuel, waste cooking oil biodiesel, and ultra-low sulfur diesel using a Well-to-Exhaust framework

The conversion of plastic solid waste and waste cooking oil into useful alternative fuels, e.g., waste plastic fuel and biodiesel, respectively, helps mitigate waste accumulation and minimize the dependence on fossil fuels, like ultra-low sulfur diesel (aka diesel). This study aims to assess the potential environmental impacts of both waste-derived fuels with the help of a scalable Well-to-Exhaust life-cycle analysis (functional unit = 1 kg of fuel) conducted within a university campus (control volume) with well-defined boundaries. The performance of both fuels is assessed on a Well-to-Pump (fuel fabrication) and Pump-to-Exhaust (end-use) basis, and their summation is used to present the life cycle impact of each fuel comparative to diesel. The findings reveal that diesel worsens the local air quality and significantly contributes to global warming. In contrast, waste plastic fuel appears to have a relatively lower impact on the air quality index and global warming, suggesting that its production near urban areas could help mitigate plastic waste accumulation and environmental pollution while boosting the local economy. On the other hand, biodiesel emerges as a relatively cleaner fuel and shows significantly lower emissions, especially during its fabrication. Therefore, its manufacture and end-use can be decoupled to enhance the economics of the process. Finally, its lowest overall carbon dioxide emissions hint that its use could be instrumental in lowering greenhouse gas emissions.