Experimental simulation of hard coal underground gasification for hydrogen production

► A two-stage UCG of hard coal was investigated in a special surface reactor. ► Underground conditions were imitated both in respect to the coal seam and the surrounding strata. ► The average hydrogen concentration during the oxygen stage was 15.28% with the maximum of 54.4%. ► The average hydrogen concentration during the steam stage was 53.77% with the maximum of 62.90%. ► The feasibility of hydrogen-rich gas production during the UCG of hard coal was demonstrated.