Low-cost copper ore oxygen carrier for Bio-CLOU systems: performance assessment and potential for negative-carbon bioenergy (BECCS)

Bioenergy with carbon capture and storage (BECCS) is recognized as a key negative-emission strategy for climate mitigation, and its large-scale implementation can be strengthened through Chemical Looping with Oxygen Uncoupling (CLOU), which enables efficient solid biomass conversion with inherent CO 2 capture. In this context, this study investigates a low-cost natural copper ore as an oxygen carrier for Bio-CLOU systems. The material (designated as CuB) was thermally treated to remove sulfur and enhance mechanical strength, and its redox performance was assessed via TGA and batch fluidized bed experiments under biomass combustion conditions. TGA results revealed a high oxygen transport capacity (R OC,CLC = 19.1%) and significant oxygen uncoupling capability (R OC,CLOU = 3.9%), with stable performance over cycles. BFBR experiments demonstrated rapid regeneration and sustained oxygen release up to 950 °C, including under low oxygen concentrations (5 vol% O 2 ), conditions compatible with biomass-based systems. Physicochemical characterization confirmed the structural stability and magnetic separability of CuB after prolonged redox cycling, although a slight decrease in mechanical strength was observed. The combination of high reactivity, efficient oxygen uncoupling capacity, operational stability, and low-cost natural origin positions CuB as a highly promising oxygen carrier for scalable Bio-CLOU applications, enabling renewable energy generation with inherent CO 2 capture and potential negative emissions. • A copper ore was optimized and evaluated as a low-cost oxygen carrier for CLOU and Bio-CLOU. • CuB showed high oxygen transport (R OC,CLC = 19.1%) and uncoupling capacity (R OC,CLOU = 3.9%). • Long-term batch fluidized-bed tests demonstrated low attrition rates and fast regeneration. • Magnetic susceptibility enables potential recovery from biomass-derived ash streams. • CuB represents a sustainable alternative for CO 2 -capture processes, supporting Bio-CLOU/BECCS renewable-energy applications.