Thermodynamic analysis of compressed CO <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si64.svg" display="inline" id="d1e2506"> <mml:msub> <mml:mrow/> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msub> </mml:math> energy storage in salt caverns with gravel stabilization
Jan Štěpánek, W. Minkley, Jan Syblík, Václav Dostál
Abstract
Efficient energy storage with large capacity is necessary for the future development of the energy sector, which will be partly based on renewable energy sources. These energy sources are variable in both time and space and surplus energy must be stored at times of high output and extracted when necessary. At present, pumped storage plants and, to a lesser extent, compressed air storage are such storage facilities. In this study, a thermodynamic analysis of energy storage with compressed CO2 in a closed system of two caves is performed. In addition, to increase the thermodynamic efficiency, this system is equipped with gravel as a thermal capacity term. Results from more than 420 configurations show that such a storage system can achieve efficiencies of over 60% and powers of over 100 MW depending on boundary conditions. The maximum electrical energy that can be generated reaches around 600 MWh. This system shows higher efficiency using CO2 than an air system without the need for above-ground heat storage installation. Aspects affecting the performance, efficiency, and capacity of the storage system are described in detail in the paper.