Biomass-to-energy integrated trigeneration system using supercritical CO2 and modified Kalina cycles: Energy and exergy analysis

Abstract

One of the main global challenges is to produce energy in a sustainable way, for example, from renewable energy sources. This study proposes a novel system for trigeneration of cold, heat, and electricity, driven by biomass gasifier. The proposed solution consists of a modified Kalina cycle and a supercritical CO2 power cycle. The input energy of the system is provided by the gasification of municipal solid wastes. In addition to electricity generation, the cold is produced at the sub-zero temperature in the modified Kalina cycle, and the absorbed heat is recovered by a heating unit in the supercritical CO2 cycle. The high thermal energy of the exhaust gases is used to increase the temperature of CO2 entering a gas turbine and then is directed to a boiler to run the Kalina cycle. The thermodynamic relations governing the gasifier, CO2 and Kalina cycles are developed using the engineering equation solver (EES) software. As a result of thermodynamic modeling, from 3.683 kg/s of syngas the energy and exergy efficiency at 71.45% and 55.43% can be achieved, respectively. Furthermore, the highest exergy loss is found to be 7.604 kW and 2.839 kW in the gasifier and combustion chamber, respectively.