Experimental demonstration of 80 kWth chemical looping combustion of biogenic feedstock coupled with direct CO2 utilization by exhaust gas methanation

Abstract

Chemical looping combustion is a highly efficient CO2 separation technology without direct contact between combustion air and fuel. A metal oxide is used as an oxygen carrier in dual fluidized beds to generate clean CO2. The use of biomass is the focus of current research because of the possibility of negative CO2 emissions and the utilization of biogenic carbon. The most commonly proposed OC are natural ores and residues, but complete combustion has not yet been achieved. In this work, the direct utilization of CLC exhaust gas for methane synthesis as an alternative route was investigated, where the gas components CO, CH4 and H2 are not disadvantageous but benefit the reactions in a methanation step. The whole process chain, the coupling of an 80 kWth pilot plant with gas cleaning and a 10 kW fluidized bed methanation unit were for this purpose established. As OC, ilmenite enhanced with limestone was used, combusting bark pellets in autothermal operation at over 1000 °C reaching high combustion efficiencies of up to 91.7%. The fuel reactor exhaust gas was mixed with hydrogen in the methanation reactor at 360 °C and converted with a methane yield of up to 97.3%. The study showed especially high carbon utilization efficiencies of 97% compared to competitor technologies. Based on the experimental results, a scale-up concept study showed the high potential of the combination of the technologies concerning the total efficiency and the adaptability to grid injection. Graphical Abstract

Energetic, Exergetic, and Techno-Economic Analysis of A Bioenergy with Carbon Capture and Utilization Process via Integrated Torrefaction–CLC–Methanation

“…Kermani and Houshfar [45] analyzed the energetic and exergetic performance of a biomass (wood chips and wheat straw chopped wood) combustion plant integrated with post-combustion CO 2 separation via absorption and subsequent methanation. Recently, Fleiß et al [46] successfully demonstrated the operation of an 80 kW th CLC unit fed by bark mulch with direct utilization of the flue gas stream in a fluidized bed methanator and performed a scale-up study to a 100 MW th plant. Finally, Brachi et al [9] investigated the performance of an integrated CLC-methanation plant relying on solar torrefied agro-industrial biomasses as input fuel through model computations.…”

“…BECCU with CO 2 conversion into renewable fuels is thus gaining significant attention to increase the penetration of renewable energies, reduce greenhouse gas emissions, and convert H 2 into more easily exploitable fuels [9,[43][44][45][46]. This study aims to contribute to the existing literature on the topic by estimating key energetic and economic performances of an integrated process targeting both BECCU and methane production.…”