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Evaluation of drive technology for a dry gravity energy storage system
Mugyema, M. 2025. Evaluation of Drive Technology for a Dry Gravity Energy Storage System. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0443c012-2ab6-4b79-a26d-46c4a3945467
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| Format: | Thesis |
| Language: | English |
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Stellenbosch : Stellenbosch University
2025
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| _version_ | 1867613736919891968 |
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| access_status_str | Open Access |
| author | Mugyema, Morris |
| author2 | Kamper, M. J. |
| author_browse | Kamper, M. J. Mugyema, Morris |
| author_facet | Kamper, M. J. Mugyema, Morris |
| author_sort | Mugyema, Morris |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Mugyema, M. 2025. Evaluation of Drive Technology for a Dry Gravity Energy Storage System. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0443c012-2ab6-4b79-a26d-46c4a3945467 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132260 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:40:53.839Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132260 Evaluation of drive technology for a dry gravity energy storage system Mugyema, Morris Kamper, M. J. Wang, R. J. Sebitosi, A. B. Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Energy storage -- Equipment and supplies Permanent magnet motors Renewable energy sources Mathematical optimization Finite element method UCTD Mugyema, M. 2025. Evaluation of Drive Technology for a Dry Gravity Energy Storage System. Unpublished doctoral dissertation. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/0443c012-2ab6-4b79-a26d-46c4a3945467 Thesis (PhD)--Stellenbosch University, 2025. ENGLISH ABSTRACT: Amid mounting environmental concerns linked to the significant carbon dioxide emissions from fossil fuel usage, there’s been a focused push towards adopting Renewable Energy Sources (RES). Nevertheless, the unpredictable nature of these renewable sources has brought about operational and control uncertainties into the grid. This unpredictability presents a notable obstacle to the widespread integration of RES into the grid. The uncertainty surrounding renewable energy generation highlights the necessity for a robust and flexible network to efficiently manage the balance between supply and demand. In tackling these obstacles, energy storage systems have emerged as promising solutions to alleviate the impacts of intermittency and enhance the overall flexibility and stability of the grid. Among these, a newly proposed Linear Electric Machine Gravity Energy Storage System (LEM-GESS) has exhibited significant promise, particularly for primary response applications. LEM-GESS boasts distinctive advantages, including its geographical flexibility, modular design, and scalability. With notable features such as long cycling capability and prolonged lifespan, LEM-GESS emerges as a compelling solution for large-scale energy storage requirements. Nonetheless, uncertainties persist concerning the linear drive unit and the Levelized Cost of Storage (LCOS) associated with the system. A prior investigation into the potential of the LEM-GESS highlighted that various machine performance characteristics such as efficiency, power factor, and material mass significantly impact the system’s overall performance and cost. These factors play a crucial role in determining how effectively the system operates and its economic viability. Therefore, it is essential to conduct a thorough evaluation of different drive systems to identify the most appropriate topology for powering the LEM-GESS. This comprehensive assessment will help ensure that the chosen drive system optimally balances performance, efficiency, and cost-effectiveness. The objective of this study is to assess various linear drive units suitable for the LEM-GESS. A design optimization technique based on finite element analysis is employed to evaluate two permanent magnet and two non-permanent magnet linear machines: the consequent pole linear vernier hybrid machine (CP-LVHM), the linear permanent magnet flux switching machine (LPM-FSM), the linear wound field flux switching machine with toroidal windings (LWF-FSM TOR), and with circumferential windings (LWF-FSM CIR). Subsequently, the Levelized Cost of Storage (LCOS) of the LEM-GESS is calculated to determine its competitiveness when utilizing the chosen PM and non-PM linear machine drive units. Through the assessment of these machines, it is observed that the LEM-GESS demonstrates favorable performance and cost competitiveness, particularly when equipped with a LPM-FSM drive unit. In order to validate the effectiveness of the finite element based design optimization methodology employed, an optimally designed prototype LPM-FSM machine is constructed, and experimentally tested. The findings of this study highlight the benefits of the LEM-GESS, demonstrating its significant competitive edge in primary frequency response application when compared with established energy storage systems like lithium-ion batteries, leadacid batteries, vanadium redox flow batteries, and flywheels. Furthermore, this research offers profound insights into the broader potential of the LEM-GESS as a large scale dry gravity energy storage solution. AFRIKAANSE OPSOMMING: Geen opsomming beskikbaar. Doctoral 2025-06-02T06:42:29Z 2025-06-02T06:42:29Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132260 en Stellenbosch University xxii, 148 pages : ill.ustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Energy storage -- Equipment and supplies Permanent magnet motors Renewable energy sources Mathematical optimization Finite element method UCTD Mugyema, Morris Evaluation of drive technology for a dry gravity energy storage system |
| title | Evaluation of drive technology for a dry gravity energy storage system |
| title_full | Evaluation of drive technology for a dry gravity energy storage system |
| title_fullStr | Evaluation of drive technology for a dry gravity energy storage system |
| title_full_unstemmed | Evaluation of drive technology for a dry gravity energy storage system |
| title_short | Evaluation of drive technology for a dry gravity energy storage system |
| title_sort | evaluation of drive technology for a dry gravity energy storage system |
| topic | Energy storage -- Equipment and supplies Permanent magnet motors Renewable energy sources Mathematical optimization Finite element method UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132260 |
| work_keys_str_mv | AT mugyemamorris evaluationofdrivetechnologyforadrygravityenergystoragesystem |