11,000 h of chemical-looping combustion operation—Where are we and where do we want to go?

•Chemical-Looping Combustion (CLC) operational experience is more than 11,000 h.•Ideally, no gas active separation is needed in CLC as carbon capture is inherent.•CLC has a unique potential for reducing cost and energy penalty of carbon capture.•A large number of oxygen-carrier materials suitable for CLC have been identified.•CLC can be used with most fuels, including biomass which gives negative emissions.