Environmental assessment of Waste-to-Energy plants using Ecological Efficiency method

• Grant number: 25/04265-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Engineering - Sanitary Engineering - Basic Sanitation
• Principal Investigator: Maria Luisa Nerys de Moraes Carneiro
• Grantee: Pedro de Souza Assunção
• Host Institution: Instituto de Geociências e Ciências Exatas (IGCE). Universidade Estadual Paulista (UNESP). Campus de Rio Claro. Rio Claro , SP, Brazil

Abstract

Most urban solid waste in Brazil is sent to landfills. However, according to the principles of Circular Economy and Sustainability, this practice is considered obsolete and does not align with the guidelines of the National Solid Waste Policy. More sustainable alternatives involve converting waste into renewable energy sources, such as in Waste-to-Energy (WtE) plants, which are beginning to be implemented in some Brazilian states.WtE plants offer the advantage of significantly reducing both the volume and hazardous nature of waste almost instantly while also minimizing the need for landfills. However, waste combustion generates gas emissions that require advanced environmental control systems. To assess the environmental impact of WtE plants, it is essential to measure their effects holistically, a process that typically involves complex evaluations and numerous variables.The Ecological Efficiency (EE) indicator emerges as an alternative for quantifying the ecological footprint of different energy systems in a more practical way than traditional methods. Its methodology combines thermal efficiency-the ratio of input energy to useful output energy-with the impacts of gas emissions on global warming and human toxicity.This study proposes the application of the Ecological Efficiency method to different advanced configurations of WtE plants, which thermally convert municipal solid waste (MSW) into electricity through high-efficiency incineration systems. Additionally, hybrid combined-cycle WtE plants will be evaluated, which utilize a combination of MSW and biogas, biomethane, or natural gas burned in gas turbines.The proposed methodology consists of quantifying the environmental performance of different WtE layouts using the Ecological Efficiency indicator. To achieve this, computational models of the thermodynamic configurations of WtE plants will be employed, allowing simulations of their operation and estimation of key variables needed for EE calculation. Some gas emissions not accounted for in the model will be obtained from the literature. Furthermore, sensitivity analyses will be conducted to assess the environmental performance of WtE plants based on variations in factors such as the calorific value of waste, ambient temperature, and fuel ratio.This study will contribute to a better understanding of the ecological footprint of Waste-to-Energy plants and the development of more sustainable energy solutions for municipal solid waste management. (AU)