Thermodynamic analysis of a novel fossil‐fuel–free energy storage system with a trans‐critical carbon dioxide cycle and heat pump

Abstract

This paper presents and analyzes a novel fossil-fuel-free trans-critical energy storage system that uses CO2 as the working fluid in a closed loop shuttled between two saline aquifers or caverns at different depths, one a low-pressure reservoir, and the other a high-pressure reservoir. Thermal energy storage and a heat pump are adopted to eliminate the need for external natural gas for heating the CO2 entering the energy recovery turbines. We carefully analyze the energy storage and recovery processes to reveal the actual efficiency of the system. We also highlight thermodynamic and sensitivity analyses of the performance of this fossil-fuel-free trans-critical energy storage system based on a steady-state mathematical method. It is found that the fossilfuel-free trans-critical CO2 energy storage system has good comprehensive thermodynamic performance. The exergy efficiency, round-trip efficiency, and energy storage efficiency are 67.89%, 66% and 58.41%, and the energy generated of per unit storage volume is 2.12 kW⋅h/m 3 , and the main contribution to exergy destruction is the turbine re-heater, from which we can quantify how performance can be improved. Moreover, with a relatively higher energy storage and recovery pressure and lower pressure in the low-pressure reservoir, this novel system shows promising performance.

Power prediction of waste heat recovery system for a cement plant using back propagation neural network and its thermodynamic modeling

“…To show less reliance on fossil fuel, Hao et al presented a thermodynamic analysis of a fossil fuel free energy storage system with an investigation on the operational behavior of its key parameters. 35 By surveying the literature and considering the WHRS in a cement plant, it was clear that predicting the electrical power produced by the turbine using neural network was never undertaken. Accordingly, the main objective of this study was to apply ANNs to predict the generated power as well as investigate the actual performance of a WHRS.…”

“…Utilization of solar energy reduced the consumption of fossil fuel in the plant, whereas the efficiency of the system was not altered much. To show less reliance on fossil fuel, Hao et al presented a thermodynamic analysis of a fossil fuel free energy storage system with an investigation on the operational behavior of its key parameters 35 …”

An innovative s olar‐powered natural g as‐based compressed air energy storage system integrated with a liquefied air power cycle

“…Their results indicated that the energy efficiency of these systems was between 52% and 59.6% 25 . Hao et al 26 proposed a novel energy storage system similar to a conventional CAES system that utilizes carbon dioxide as its working fluid, and also, used a heat pump to eliminate the use of natural gas in the discharging mode. Energetic and exergetic efficiencies of the system were obtained as 58.4% and 67.9%, respectively 26 .…”

“…Hao et al 26 proposed a novel energy storage system similar to a conventional CAES system that utilizes carbon dioxide as its working fluid, and also, used a heat pump to eliminate the use of natural gas in the discharging mode. Energetic and exergetic efficiencies of the system were obtained as 58.4% and 67.9%, respectively 26 . An integrated wind/solar‐based CAES system was investigated by Ji et al 27 The round‐trip and exergy efficiencies of the proposed system were 61.2% and 65.4%, respectively 27 .…”

Thermodynamic analysis of a novel compressed carbon dioxide energy storage system with low‐temperature thermal storage

“…Liu et al 24 proposed a two‐reservoir CCES system, and they used a steady‐state mathematical model to evaluate the performance of the idealized two‐reservoir CCES system with a high‐temperature heat source (>800 K). Hao et al 25 proposed a novel transcritical CO 2 energy storage system with two saline aquifers or caverns at different depths and studied the operating characteristics under different depth conditions.…”