Energy balance calculation of selected refinery concepts for Energy from Waste facilities

Abstract

Three different EfW (Energy from Waste) scenarios are constructed consisting of combinations of incineration, gasification, anaerobic digestion, and fuel cell technology. Each scenario represents different EfW concepts but uses the same basic structure and operational condition. All scenarios consist of two waste treatment processes; thermal and biological treatment. The first scenario is an adaption of the Borås waste treatment facility reference case where fluidized bed CHP cycle is used to incinerate combustible waste and anaerobic digestion is used for biological waste. The second scenario is foreseeable future concept where gasification and incineration take place. The third is scenario is the futuristic scenario where waste is gasified and used in fuel cell for electricity conversion. The three scenarios have the same biological process where waste turns into biogas and upgrade for high methane concentration. In order to investigate the energy production, an energy and mass balance calculation for each scenario was made using information collected from actual waste treatment facility and literature data. The balance model was created and evaluated using performance data collected from actual plant, literature data, and estimations. The biological process is based on the Sobacken biogas plant and Läckeby water biogas upgrade plant. The energy from waste reference case with 100 000 ton combustible wastes and 30 000 ton biological waste produce 18.4 GWh of 97.5% methane biogas, 62.7 GWhe and 220 GWhheat annually. Using the same structure and operation condition, Scenario 1 produced 26 GWh of 97.5% methane biogas, 62.7 GWhe and 214.12GWhheat. The second scenario with gasification using gas turbine and steam cycle produce 26 GWh of 97.5% methane biogas, 70.1 GWhe and 181.61 GWhheat. The third scenario with gasification and fuel cell technology produced 26 GWh of 97.5% methane biogas, 81.7 GWhe and 93.4 GWhheat. The integration of gasification in second and third scenario has affected the heat and electricity production of the power plant. Considering the heat and power generation on the sustainable perspective, the third scenario is the best option for Energy from waste.