Design and Performance Assessment of a Novel Poly-generation System with Stable Production of Electricity, Hydrogen, and Hot Water: Energy and Exergy Analyses

The present investigation proposes an innovative hybrid energy system based on solar energy equipped with a parabolic trough collector, a supercritical CO₂ Brayton cycle (SCBC), a recuperative organic Rankine cycle (RORC), a proton exchange membrane electrolyzer (PEME), and a two-tank direct thermal energy storage system. To ensure the stable operation of the system despite fluctuations in the amount of sunlight received during the day, the mass flow rate (MFR) of the heat transfer fluid in the solar collector is regulated to maintain a consistent inlet temperature for the SCBC and RORC. Additionally, the MFR of the HTF from the hot tank to the bottoming cycles also remains constant. This approach allows the entire system to operate around the clock and under stable conditions. The energy and exergy performance of the entire system is evaluated under varying solar irradiance and ambient temperature over a 24-h period. The results revealed that the system could generate 1.5 MW of net power, 4.47 kg of hydrogen per day, and 18.48 kg/s of hot water with a total energy efficiency of 51.30% and exergy efficiency of 55.7%. The solar collector possessed the lowest exergy efficiency of 33.89% due to a high exergy destruction rate. The PEME possessed maximum energy efficiency of 58.85%, followed by RORC and SCBC with 26.38% and 14.84%, respectively. It is concluded the proposed system can provide a reliable and sustainable supply of electricity, hydrogen, and hot water, demonstrating a promising and viable poly-generation technology for both grid-connected and off-grid applications.