Modelling of a combined biomass CLC combustion and renewable-energy-based methane production system for CO2 utilization.

In this paper, an innovative process layout to promote the integration among the chemical looping combustion of biomass, solar hydrogen, and carbon methanation is proposed and numerically investigated. The core of the layout consists of a multiple interconnected fluidized bed (MFB) system for the chemical looping combustion of solid fuels. A coupled hydrodynamic and reactive model of the system was developed and applied to evaluate solid circulation rate, solid bed levels in different parts of the system, flue gas composition and flow rate, and power production. The performance of the system was evaluated by considering chemical and physical properties of olive wood, a biomass typical of Mediterranean area, as fuel and of CuO supported on zirconia as oxygen carrier, respectively. A complex reaction scheme comprising both gas–solid heterogeneous and gas-phase homogeneous reactions was considered. Results corresponding to steady state operation of MFB are presented in conjunction with an analysis of the operability of the system under the considered ranges of operating conditions. By considering that only energy coming from renewable sources (such as photovoltaic panels or wind turbines) was fed to the electrolysis cell (EC) array, the potential of the proposed process to be used as an energy storage system was assessed. Unlabelled Image • A mathematical tool for evaluating the performances of a novel system was developed. • Heat and mass balances were coupled with thermodynamic and hydrodynamic model. • Through numerical simulation, system steady state operation ranges were evaluated. • High CH 4 yield can be reached only accounting for at least two methanation units. • A 17% electric energy storage efficiency can be achieved, as long as near-zero CO 2 emissions. [ABSTRACT FROM AUTHOR]