Combined Chemical Looping: New Possibilities for Energy Storage and Conversion

Abstract

A novel concept of energy storage and conversion was demonstrated in a laboratory-scale test. The proposed combined chemical looping is able to store and release energy from chemical looping combustion for heat generation and hydrogen production by steam–iron processes integrated in one reactor. The reactor contains two concentric chambers, which are both filled with iron-based material. In a first step, all material is reduced to the metallic form, thus “charging” the reactor. For the second step or “discharging”, steam is fed to the inner chamber and air is fed to the outer chamber. The inner chamber is used for hydrogen production, and the external chamber is used for heat generation. In addition to iron, the external chamber contains a highly pyrophoric Ni-based layer at the air entry point to enable the startup of heat generation at room temperature. This concept of combined chemical looping was successfully tested: heat was generated by metal oxidation in air, and H2 was produced following contact o...