Hybrid hydrogen energy storage system assisted by cold storage Rankine Carnot battery for power and heat production: Performance assessment and multi-objective artificial hummingbird optimization algorithm

Energy storage is an effective solution for solving grid volatility of renewable electricity. The hydrogen energy storage (HES) system is a promising energy storage technology due to the high energy density of hydrogen as an energy storage medium. In this work, a new HES system, including the proton exchange membrane electrolyzer (PEME), the solid oxide fuel cell (SOFC), and the waste heat recovery supercritical CO₂ recompression cycle (SRC) is proposed to produce power and heat load without CO₂ emission. To enhance the roundtrip efficiency of the HES system, a cold energy storage Rankine Carnot battery (CSRCB) based on a vapor compression refrigeration cycle (VCR) and transcritical CO₂ regenerative Rankine cycle (TRC) is introduced to integrate the sub-ambient temperature with SRC and SOFC waste heat. The system’s performance is studied using thermodynamic and economic methods, and the effect of employing CSRCB on the roundtrip efficiency is assessed by defining a new improvement percent (IP) index. A comprehensive parametric assessment and multi-objective artificial hummingbird optimization algorithm (MOAHA) are conducted to find the maximum roundtrip efficiency and discharge power with a minimum product cost rate. According to the results, employing CSRCB enhances the roundtrip efficiency of the HES system by 74.36 % with a 30.38 % increment relative to the base point. In this case, the discharged exergy efficiency increases by 89.88 %, and the economic indicators of product cost rate, levelized cost of storage (LCOS), and payback period (PP) decline to the minimum values of 89.03 $/s, 0.2544 $/kWh and 4.47 years, respectively, with 3.65 M$ net present value (NPV).