PRODUCTION OF SOLAR HYDROGEN BY A NOVEL, 2-STEP, WATER-SPLITTING THERMOCHEMICAL CYCLE

A novel, two-step, water-splitting cycle is presented which, in contrast to previously proposed cycles that require upper operating temperatures above 2300 K, can be conducted at a moderate temperature. In the first endothermic step, Ni0.5Mn0.5Fe2O4 is thermally activated above 1073 K to form an oxygen-deficient ferrite. In the second step, activated ferrite is reacted with water below 1073 K to form hydrogen; the ferrite product is recycled to the first step. H-2 and O-2 are derived in different steps, eliminating the need for high-temperature gas separation. Both reactions have been demonstrated experimentally using concentrated solar radiation as energy source for the activation.