Use of natural ores as oxygen carriers in chemical looping combustion: A review

Chemical looping combustion (CLC) has gained considerable ground in energy production due to its inherent carbon capture with a minimal energy penalty. The choice of metal oxide used as an oxygen carrier (OC) in CLC has a substantial weight on the overall efficiency of energy production as well as the ultimate cost per MW. While much work has gone into manufacturing synthetic OCs with high fuel conversions, harsh operating conditions and process limitations cause some unavoidable loss of the oxygen carrier. With low production costs and minimal conditioning required, natural ores have grown in interest as cheap alternative oxygen carriers. This work provides a substantial literature review of recent works studying the use of natural ores in CLC. Iron-based, manganese-based, copper-based and calcium based ores were found to be the main ores researched, along with mixtures of these ores and natural ores with minor additional compounds. Typical parameters have been collected for each study including; fuel conversion, stability, physical characteristics, and carbon capture efficiency. Natural ores are compared with purified metal oxides to highlight strengths and weaknesses of each ore and recommendations for future studies are made.