Chemical looping with oxygen uncoupling of swine manure for energy production with reduction of greenhouse gas emissions

Abstract

The thermochemical conversion of swine manure using chemical looping processes is an alternative for obtaining bioenergy with CO2 capture and solving environmental problems related to excess nutrients and greenhouse gas emissions. In this study, the combustion of swine manure was performed in a chemical looping with oxygen uncoupling (CLOU) unit at the 0.5 kWth scale with copper-based oxygen carrier particles supported on magnetic MnFe spinel. The effects of the fluidisation agent (CO2 or steam), air excess (7%–23%), and temperature (800–950 °C) on different parameters, namely the CO2 capture rate, combustion efficiency, and nitrogenous compound emissions, were analysed. High combustion efficiencies (95%–98%) were achieved, and tar compounds were not detected in the flue gases. Similarly, elevated CO2 capture efficiency values (82%–99%) were also achieved, which increased by increasing the temperature. Most nitrogen (ca. 93%–96%) is converted into innocuous N2. The NO concentration increased with temperature, whereas N2O and NH3 concentrations decreased.