Geothermal Sourced Trigeneration Plant for Puga Valley: Techno-Economic Analysis and Multi-Objective Optimization

The techno-economic feasibility of a binary geothermal trigeneration plant customized for the Puga Valley, India, was examined for the concurrent generation of power and green hydrogen, in addition to district heating. This study considers the unique geotechnical data of the Puga Valley, including geothermal gradients for individual gauged wells and related cost functions. The primary mover of the trigeneration plant is a dual-loop organic Rankine cycle (ORC), with R123 as the primary working fluid and R125 as the secondary working fluid. The bottoming ORC loop was coupled with a proton-exchange membrane electrolyzer, harnessing its net power to produce green hydrogen. Geothermal resources are used to generate thermal energy for district heating, thereby increasing the overall efficiency of the plant. The overall effectiveness and cost of the system are significantly affected by variations in operational and design factors, such as the temperature, fluid flow rate of the geothermal source, and ORC turbine inlet temperature. An artificial neural network-based multi-objective optimization study was conducted to ascertain the optimum values for the aforementioned parameters. The outcome represents an optimal Pareto curve, with the objective functions being the trigeneration plant's overall cost rate, electricity yield, and exergy efficiency. The proposed trigeneration plant could simultaneously produce 1.1 MW of electricity, 5.7 kg/h of green hydrogen, and 789.2 kW of thermal energy for the district heat network at a supply temperature of 85 degrees C at the optimal operating point. The corresponding values for the overall energy efficiency, exergy efficiency, and total cost rate were determined as 17.2 %, 38 %, and 56.8 US$/h, respectively.