Waste-to-energy technology selection and capacity planning in a multi-facility waste management system

Waste-to-energy (WtE) technologies provide a viable solution for dealing with the large quantities of municipal solid waste (MSW) generated in modern societies. However, they must be optimally integrated with waste management and energy distribution networks to maximize their economic and environmental benefits. A strategic optimization model is proposed for locating waste processing facilities, allocating MSW-generating communities to them, determining the types and capacities of equipment in each, and directing the flow of energy products (electricity, heat, and hydrogen) from them to demand nodes, aiming to achieve two objectives: maximizing profit and minimizing greenhouse gas emissions. The cost, emission, and conversion functions of three WtE technology alternatives (TAs) are meticulously derived so they can be incorporated into the mathematical model. The proposed approach is applied to a realistic case study in Nova Scotia, Canada. Results show that the type and location of WtE technologies depend on the objective sought, the cost structure of TAs, and the price of energy products. Plasma arc gasification with hydrogen separation is found to be the most economically viable WtE technology due to the high value of hydrogen it produces, whereas anaerobic digestion with combined heat and power has the lowest carbon footprint. Sensitivity analysis revealed that the optimal WtE system configuration is quite sensitive to the price of hydrogen, while the technology capacity lower limit barely changes the system's economic and environmental performance. Conversely, variations in waste composition and subsidy policies caused no change in the profit-maximizing system configuration.