Economic Analysis and Life Cycle Assessment of Pyrolysis of Plastic Waste in Mumbai, India

Abstract

Most of the municipal solid waste (MSW) generated in metropolitan cities in India is dumped unscientifically, leading to environmental and health disasters. Plastic waste, a considerable fraction of the urban MSW, is a major concern. Around 700 tonnes of plastic waste is generated in Mumbai every day. Plastic waste, however, can be a valuable source with the potential to generate energy and value-added products such as oil, gas and char through pyrolysis. However, it is important to assess the suitability of this option by comparing the economic and environmental dimensions so that an appropriate policy guideline can be developed. This work performs such a detailed assessment for the city of Mumbai. The MSW is assumed to be separated at source so that plastic waste is available for pyrolysis. The process includes shredding followed by pyrolysis. The oil obtained is sold as a fuel, while the gas is used to produce electricity after meeting the energy demand of pyrolysis. Detailed cost calculations are performed for the complete plastic waste generated in Mumbai. The costing is performed using concepts of equipment design, sizing and economics. Concurrently, detailed life cycle assessment (LCA) is performed to quantify the environmental impacts. LCA inventory is generated using data from literature as well as the ecoinvent database. OpenLCA along with ILCD midpoint impact assessment method is used for impact assessment with 1 tonne of plastic waste as the functional unit. The results show that a net profit of INR 7047 per tonne of plastic waste is generated. The LCA results show that the impacts to be 52.34 kg CO2 eq., 29.53 CTUe and 1.78 × 10−6 CTUh for climate change, freshwater ecotoxicity, and human toxicity (carcinogenics), respectively. These results can be compared with other options such as landfill and composting to provide customized MSW management guidelines.