Session: ASME Undergraduate Student Design Expo

Paper Number: 175870

Urban Waste and Power: Designing a Next Generation Waste-to-Energy Power Plant in St. Louis, Mo 

In August 2025, the city of St. Louis, Missouri, announced that it would permanently end its alley recycling program due to ineffectiveness and high costs, instead choosing to focus on regular garbage collection. Considering that before this change, St. Louis only recycled approximately 11% of trash by tonnage, this represents a major step back in sustainability for the region. Although recycling drop-off locations will remain in operation, most households will no longer have a convenient way to recycle without making a special trip. Thus, new innovative solutions to sustainably manage municipal solid waste (MSW) are required.

This study explores the design of a new waste-to-energy (WtE) power plant in the city of St. Louis, designed to incinerate local MSW and sustainably generate electricity for the grid. The proposed facility is designed to incinerate up to 500,000 tons of MSW annually, a capacity comparable to the 533,955 tons processed by the two largest transfer stations in St. Louis and the surrounding metro area. Goals of the project include a thermal efficiency competitive with other WtE plants, an advanced emission system to reduce harm to the surrounding area, and a high net power output to supply energy to the grid. The methodology used for design and analysis of the power plant included simulations using the chemical process simulator DWSIM (v. 9.0.4), analysis of processes in existing operational WtE plants, and comparison of the calculated results to those of existing operational WtE plants.

Using trash composition data from a state-wide audit in 2018, a mathematical model based on physical composition was used to calculate the average higher heating value (HHV) of St. Louis MSW at 18.14 MJ/kg, with a corresponding lower heating value (LHV) of 15.92 MJ/kg after accounting for moisture. At maximum capacity, this translated to 229 MW of thermal energy released in the boiler. Process modeling as a Rankine cycle, with an 8:1 air-to-fuel ratio, 55 kg/s water flow rate, and turbine inlet pressure of 140 bar, yielded a net electrical output of 48.8 MW. This corresponded to an overall thermal efficiency of 21.3%, a value that can be compared to operational WtE plants. In addition, the potential use of a flue gas heat recovery system to generate up to 34.7 MW of district heating was explored.

A common problem with WtE plants is the undesirable fumes and noxious smells that they can produce. A priority of the study was to design the power plant in a way that contributed to the surrounding urban environment and to avoid industrial blight. Inspiration is taken from European WtE plants such as Amager-Bakke in Copenhagen which have shown great success in utilizing new technologies to reduce harm to the surrounding area and integrate into the urban fabric. To greatly reduce airborne toxins and particulates, advanced emission remediation processes were explored such as selective catalytic reduction (SCR), spray-dry absorbers (SDA), and pulse-jet fabric filters. By doing so, this project aims to be one of the cleanest power plants in the United States and lead the way in sustainability and forward-thinking waste management for an urban area.

Presenting Author: Aedan Bird Saint Louis University

Presenting Author Biography: Aedan Bird is a senior Mechanical Engineering student at Saint Louis University. Some of his current academic interests include thermal systems design, mobile robots, and sustainability.

Authors:

Aedan Bird Saint Louis University
Jason Wong Saint Louis University
Ethan Martin Saint Louis University
Danny Bui Saint Louis University
Derian Ryker Saint Louis University
Danahe Marmolejo Saint Louis University