Heat Recovery Unit Integrated with Biomass Gasification for Producing Hydrogen/Power/Heat Using a Novel Cascaded ORC with Biphenyl/Diphenyl Oxide Mixture; ML Optimsation and Economic Evaluation

This work provides a detailed evaluation of a novel biomass-fueled multigeneration system, conceived to contribute to the growing emphasis on sustainable energy solutions. The architecture comprises a biomass gasifier, an innovative cascaded organic Rankine cycle (CORC) incorporating a high-temperature mixture in the top cycle, a proton exchange membrane electrolyzer (PEME), a Brayton cycle, and waste heat utilization units, all operating together to deliver electricity, hydrogen (H2), and thermal output. A comprehensive thermodynamic modeling framework is established to evaluate the system’s performance across various operational scenarios. The framework emphasizes critical metrics, including exergy efficiency, levelized total emissions (LTE), and payback period (PP). These indicators ensure a holistic assessment of energy, exergy, economic, and environmental considerations. Parametric studies demonstrate that enhancements in biomass mass flow rate and combustion chamber temperature significantly increase power output and H2 production while reducing the payback period, underscoring the system’s flexibility and economic feasibility. Furthermore, the study employs sophisticated machine learning optimization methods, combining artificial neural networks (ANNs) with genetic algorithms (GA), to determine optimal operating conditions with minimal computational effort and maximum efficiency. When evaluated at nominal parameters, the system records an exergy efficiency of 23.72 %, achieves a PP of 5.61 years, and yields an LTE value of 0.34 ton/GJ. However, under optimized conditions, these values improve to 35.01 %, 3.78 years, and 0.241 ton/GJ, respectively.