Thermal technology scales in future waste management strategies

Abstract

Cities demand a large proportion of energy supplies while exporting significant amounts of municipal solid waste (MSW). Landfill regulations, self-sufficiency and proximity principles have induced shifts in waste management techniques. Historically, energy security, best use of resources, renewable energy use and climate change mitigation have not been leveraged in waste management strategies. This study examines emerging treatment technologies that could make a contribution in the aforementioned areas and have the potential for working at smaller scales in urban locations. The energy efficiency and environmental and economic performance of two thermal treatment technologies are presented, thus elucidating their potential role in urban strategies in the light of rising energy prices, decarbonisation of the economy, taxation and full use of incentives. The study illustrates that considering the full life cycle, beyond waste management, will enable more strategic technology utilisation. Improvements in viability over time according to evolving regulations are assessed, demonstrating how possible contributions to renewable heat and power can enhance profitability. Combustion technology is analysed for a medium-scale configuration, processing 100 kilotonnes per annum (ktpa) using a steam turbine for heat and power generation, and a large-scale 250 ktpa configuration. Fluidised bed gasification is analysed at the small scale (50 ktpa) and medium scale (100 ktpa) using a combined cycle gas turbine (CCGT) for heat and power generation. One key aspect is the evaluation of the processing of waste into a predominantly renewable fuel capable of running a gas and steam turbine while rendering a significant proportion of residues reusable. Emission profiles and mass and energy balances are presented quantitatively. A discounted cash flow of material and energy outputs incorporating the effect of incentives across deployment scenarios is presented. Furthermore, key technical and policy pre-conditions are discussed.