Comparative multi-aspect study of two scenarios and optimization of the biomass-based cogeneration system integrated with the carbon capture and utilization technology

Abstract

Combined Heat and Power (CHP) system based on bio-energy is an energy-saving and environment friendly way to utilize energy, but in the background of the "carbon peaking and carbon neutrality" strategy, ensuring low-carbon operation of CHP systems becomes imperative. In this paper, we introduce two distinct CHP system scenarios based on post-combustion carbon capture technologies: a syngas-based gas turbine cycle CHP system (scenario 1) and a biogas-based steam turbine cycle CHP system (scenario 2). Then, a techno-economic evaluation has been conducted to investigate their performance under varying operational conditions of heating and power load, as well as carbon capture technology. The findings reveal that, given the same biomass input rate, the syngas-based CHP system yields superior energy and economic outcomes. To simultaneously mitigate CO2 emissions and reduce electricity costs, a process of multi-objective optimization is employed. This optimization endeavor also focuses on maximizing the overall exergy efficiency. Consequently, scenario 1 experiences substantial improvements in performance metrics. Notably, the overall energy and exergy efficiencies reach 17.32 % and 14.58 % respectively. Additionally, the power and heating load are estimated at 2.58 and 2.17 MW correspondingly. The levelized cost of electricity and heating are assessed at 30.55 USD/MWh and 36.05 USD/GJ, respectively, coinciding with a reduction in CO2 emissions to 98.27 kgCO2/MWh.