Optimal Maintenance Scheduling for a Waste-to-Energy Combined Heat and Power Plant Under Uncertainty

Waste management and energy crisis are two compelling challenges worldwide due to the population growth, economic development, and rising living standards in both developed and developing countries. Waste-to-energy (WtE) technologies, which turn waste into energy, provide elegant and effective solutions to these challenges. Because of the high overall thermal efficiency, modern WtE plants are often combined heat and power (CHP) producers which generate power and heat simultaneously. WtE CHP plants are often integrated into a district heating network and they also sell electricity on commercial terms. To ensure the continuous operation of WtE CHP plants, preventive maintenance scheduling is a significantly important task for plant operators. This paper studies the optimal preventive maintenance scheduling strategy for a WtE CHP plant which exports heat to a district heating network and sells electricity in a deregulated electricity market. Since the maintenance scheduling strategy has to be determined months before the actual actions, many key parameters are uncertain or partly predictable at the time of planning the maintenance. These parameters include future electricity prices, district heating demand, and the amount of waste delivered to the plant. To address the problem, we develop a two-stage robust optimization model considering different types of uncertainty. We also design a solution procedure based on the column-and-constraint generation method to solve the model. To illustrate the effectiveness of the proposed model and the solution procedure, a case study is performed based on real-world data. Moreover, a sensitivity analysis is conducted to investigate the impacts of different types of uncertainty on the optimal maintenance scheduling strategies for the WtE CHP plant.