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Thermodynamic analysis of a novel fossil‐fuel–free energy storage system with a trans‐critical carbon dioxide cycle and heat pump
Author(s) -
Hao Yinping,
He Qing,
Liu Wenyi,
Pan Lehua,
Oldenburg Curtis M.
Publication year - 2020
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.5130
Subject(s) - exergy , energy storage , energy recovery , exergy efficiency , compressed air energy storage , environmental science , fossil fuel , process engineering , thermal energy storage , volume (thermodynamics) , working fluid , thermal efficiency , petroleum engineering , waste management , engineering , mechanical engineering , thermodynamics , chemistry , energy (signal processing) , power (physics) , statistics , physics , mathematics , organic chemistry , combustion
Summary This paper presents and analyzes a novel fossil‐fuel–free trans‐critical energy storage system that uses CO 2 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 CO 2 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 fossil‐fuel–free trans‐critical CO 2 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 reheater, from which we can quantify how performance can be improved. Moreover, with a higher energy storage and recovery pressure and lower pressure in the low‐pressure reservoir, this novel system shows promising performance.