Comparative Analysis of Isochoric and Isobaric Adiabatic Compressed Air Energy Storage

Daniel Pottie (), Bruno Cardenas, Seamus Garvey, James Rouse, Edward Hough, Audrius Bagdanavicius and Edward Barbour
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Daniel Pottie: Centre for Renewable Energy System Technology (CREST), Loughborough University, Loughborough LE11 3TU, UK
Bruno Cardenas: Faculty of Engineering, Nottingham University, Nottingham NG7 2RD, UK
Seamus Garvey: Faculty of Engineering, Nottingham University, Nottingham NG7 2RD, UK
James Rouse: Faculty of Engineering, Nottingham University, Nottingham NG7 2RD, UK
Edward Hough: British Geological Survey, Nottingham NG12 5GG, UK
Audrius Bagdanavicius: School of Engineering, University of Leicester, Leicester LE1 7RH, UK
Edward Barbour: Centre for Renewable Energy System Technology (CREST), Loughborough University, Loughborough LE11 3TU, UK

Energies, 2023, vol. 16, issue 6, 1-18

Abstract: Adiabatic Compressed Air Energy Storage (ACAES) is regarded as a promising, grid scale, medium-to-long duration energy storage technology. In ACAES, the air storage may be isochoric (constant volume) or isobaric (constant pressure). Isochoric storage, wherein the internal pressure cycles between an upper and lower limit as the system charges and discharges is mechanically simpler, however, it leads to undesirable thermodynamic consequences which are detrimental to the ACAES overall performance. Isobaric storage can be a valuable alternative: the storage volume varies to offset the pressure and temperature changes that would otherwise occur as air mass enters or leaves the high-pressure storage. In this paper we develop a thermodynamic model based on expected ACAES and existing CAES system features to compare the effects of isochoric and isobaric storage. Importantly, off-design compressor performance due to the sliding storage pressure is included by using a second degree polynomial fit for the isentropic compressor efficiency. For our modelled systems, the isobaric system round-trip efficiency (RTE) reaches 61.5%. The isochoric system achieves 57.8% even when no compressor off-design performance decrease is taken into account. This fact is associated to inherent losses due to throttling and mixing of heat stored at different temperatures. In our base-case scenario where the isentropic compressor efficiency varies between 55 % and 85 % , the isochoric system RTE is approximately 10% lower than the isobaric. These results indicate that isobaric storage for CAES is worth further development. We suggest that subsequent work investigate the exergy flows as well as the scalability challenges with isobaric storage mechanisms.

Keywords: ACAES; thermomechanical energy storage; isobaric CAES; thermodynamic analysis (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2023
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (4)

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