The impact of increasing demand for efficiency and reliability on the performance of waste-to-energy plants

Waste-to-energy achieves two main objectives, the reduction in volume of waste and the recovery of energy. Volume reduction of waste is part of waste management while the use of waste as a fuel presents the opportunity to obtain electrical power and heat, thereby reducing the consumption of fossil fuels. The efficiency of waste-to-energy plants is therefore of considerable interest and substantial efforts are being made to maximize energy output from many plants. Plant efficiency can be considered in a number of ways and certain factors impose restrictions on the degrees of freedom when trying to achieve greater energy recovery. First and foremost, a waste incinerator is a tool within waste management and thus the waste (fuel) usually cannot be selected for composition and consistency. The provider of the operating license, the local authority, sends most of the waste to the incinerator. The operator usually has little scope to choose the waste stream, and consequently the energy input (calorific value of the waste) can vary and as a result will influence the steam parameters. However, regardless of the amount of energy recovered, very stringent limits on emissions to the environment must be respected as well as the pure waste management aspects. This paper addresses the main technical challenges facing waste-to-energy plant operators and the difficult balancing act that must be achieved between plant emissions, reliability and efficiency.