Assessment of the chemical looping gasification of wheat straw pellets at the 20 kWth scale

•Wheat straw pellets were gasified by chemical looping with ilmenite as oxygen carrier.•Effect of temperature, oxygen-to-fuel ratio, solids inventory and circulation rate is assessed.•Successful control of the oxygen-to-fuel ratio by the air fed into the air reactor was achieved.•Syngas yield was mainly affected by char conversion and air-to-fuel ratio.•Some light hydrocarbons, low benzene and very low tar amounts were found.