Impact of waste management and conversion technologies on cost and carbon footprint - Case studies in rural and urban cities

Bioenergy pathways based on waste-to-energy (WTE) technologies are potential solutions to address two major societal challenges: climate change and a lack of sustainable municipal solid waste (MSW) diversion solutions. This study identifies and addresses the absence of an integrated decision-making framework that includes upstream operations (collection, separation, and delivery) and energy recovery technologies of the MSW supply chain. Modeling tools are developed for each WTE stage and integrated for the first time under a single cost and carbon footprint assessment framework. This framework is validated using two case studies to capture urban and rural characteristics. The first pathway includes gasification and an Internal Combustion Engine, and the second pathway consists of combustion and an Organic Rankine Cycle. The outcomes of this study show that Greenhouse Gas (GHG) emissions of the WTE pathways are slightly higher than fossil-based heating. This difference is explained by two factors. First, upstream logistics (often overlooked) are a major contributor to the net GHG emissions (36% in rural cases), and their emissions would offset the potential credits when replacing the current heating systems with the WTE pathways. Secondly, MSW is not entirely carbon neutral, and when the fossil-based carbon is accounted for, WTE pathways show higher GHG emissions for both rural (12–16%) and urban (17–19%) communities, which confirms that the WTE pathways still require more technology optimization and improvement. However, integrated framework revealed that WTE pathways are economically competent to reduce the current heating cost by up to 36% in rural and 25% in urban communities. • A new bottom-up decision making framework has been developed including all upstream and downstream stages. • Two simulation tools has been used to model upstream and downstream stages of multiple waste to energy pathways. • The new framework has been validated through two Canadian case studies covering specificities of urban and rural communities. • Plastic waste stream is included as a mix in the feedstock providing a practical recycling pathway. • Cost and GHG breakdown are used to identify conversion technology gaps for future R&D targets.