Aspen Plus modelling and techno-economic analysis of a waste-to-energy system using pyrolysis

Abstract

Waste management is of growing concern with increased waste generation, and the industry standards are becoming stricter due to climate goals and sustainable development. Waste-to-energy (WTE) systems in the form of waste incineration have been promoted as a low-carbon energy source, but nevertheless have high greenhouse gas (GHG) emissions. Pyrolysis offers an alternative way of utilizing energy which at high temperatures and in the absence of oxygen thermally decomposes material and yields products such as synthetic gas and biochar. Bodø Storstue, a development project for a new sports arena in Northern Noway, has high ambitions for sustainable development. WTE by pyrolysis has been identified as a potential step toward reducing GHG emissions. Thus, this thesis looked into the technical and economic aspects of integrating pyrolysis as a decentralized WTE system. A simulation model was built in Aspen Plus, which shows the energy and mass balance through the different modules in the system. An economic analysis was performed using MS Excel which included the levelized cost of electricity and net present value calculation. The results suggest that the electricity demand in Bodø Storstue can be met by using pyrolysis for power generation, and that carbon can be stored in biochar which reduces the emissions compared to traditional waste incineration. Future studies should include a simulation model based on tested feedstock composition which would make the simulation more representative of true conditions. The price of biochar should also be included in the economic analysis to obtain more precise conclusions about the economic conditions that impact investment decisions.