Polygeneration of Hydrogen and Power Using Chemical Looping Water Splitting with Dual Loops of Oxygen Carrier

The demand for hydrogen as a fuel, particularly in the transportation and power sectors, has recently been increasing due to its environmental benefit of clean combustion. However, the conventional technologies for hydrogen production involve an energy penalty in purification of hydrogen and the carbon dioxide capture, which reduce the process efficiency, whereas the technique of chemical looping hydrogen production (CLH) has an inherent capacity for CO2 capture and produces pure stream of hydrogen. This paper proposes modifications in the conventional three-reactor CLH setup, leading to elimination of the energy-intensive air separation unit and imparting flexibility in terms of polygeneration (hydrogen and power). The design modification for thermally integrating the air reactor, gasifier, and splitter for an oxygen carrier has facilitated two distinct oxygen carrier loops to meet the polygeneration objectives. The performance metrics based on efficiency have been utilized to assess the performance of the proposed process and demonstrate the flexibility in polygeneration. The effect of varying operational parameters such as split fraction, composition of metal oxide, and temperature of air reactor on the performance of the proposed process has also been evaluated.