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The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa
van Aarde, P. E. 2025. The Relationship Between Weather Regimes and Variable Renewable Energy Resource Potential and Variability in South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a13a2d92-b7d8-49b7-89b9-c1efb5cf610...
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Stellenbosch : Stellenbosch University
2025
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| author | Van Aarde, Paulemari Emily |
| author2 | Bekker, Bernard |
| author_browse | Bekker, Bernard Van Aarde, Paulemari Emily |
| author_facet | Bekker, Bernard Van Aarde, Paulemari Emily |
| author_sort | Van Aarde, Paulemari Emily |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | van Aarde, P. E. 2025. The Relationship Between Weather Regimes and Variable Renewable Energy Resource Potential and Variability in South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a13a2d92-b7d8-49b7-89b9-c1efb5cf6101 |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132380 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:48.111Z |
| 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 |
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| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132380 The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa Van Aarde, Paulemari Emily Bekker, Bernard Dalton, Amaris Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering. Renewable energy sources -- South Africa Climatic changes -- South Africa Energy policy -- South Africa UCTD van Aarde, P. E. 2025. The Relationship Between Weather Regimes and Variable Renewable Energy Resource Potential and Variability in South Africa. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/a13a2d92-b7d8-49b7-89b9-c1efb5cf6101 Thesis (MEng)--Stellenbosch University, 2025. ENGLISH ABSTRACT: The world is gradually moving away from fossil fuels towards variable renewable energy (VRE) sources like wind and solar power due to drivers like climate change policy, increasing energy independence away from fossil fuels, and the rapid price reductions of renewable energy generation. South Africa (SA) is following this trend, with wind and PV expected to provide 33% of electricity by 2030, based on the country’s energy policy. The energy provided by wind and solar is however variable, which poses several challenges to electricity networks. At short to medium term timescales of hours to days, wind power variability is typically caused by large-scale and long-lasting weather regimes (WRs). Quantification of the relationship between atmospheric circulation and wind and solar potential and variability is, as such, an ongoing area of research. In the South African context, fairly little research has been done in this field, despite its implications for balancing supply and demand. In this study, the hypothesis is tested that in the South African region, there exists a significant and measurable relationship between atmospheric WRs and the resource potential and variability of VRE resources. This relationship allows for the identification of specific WRs that have the strongest impact on VRE resource potential and variability. To support the testing of the formulated hypothesis five research questions were formulated. Towards answering these questions and ultimately proving the hypothesis, a review of the challenges involved in integrating VRE into power networks was conducted. This provided a comprehensive overview of existing studies and established literature on the relationship between VRE and WRs. Various methods proposed to minimize the variability in renewable energy resources were then examined. Additionally, weather classification methods were analyzed to investigate and quantify wind resource potential and variability linked to synoptic-scale circulation over South Africa. The review identified self-organizing maps (SOMs) as particularly suitable for classifying atmospheric states in this study. These reviews contributed to partially addressing the research hypothesis. Moreover, it was found that limited research has been conducted on the specific relationship between VRE variability and WRs in South Africa. An analysis of the relationship between WRs and the potential and variability of VRE resources was done for a 20-year period, from 2001 to 2020, using the ERA5 reanalysis datasets for wind, solar and geopotential heights. Synoptic scale circulation over South Africa was classified into 42 circulation archetypes using SOMs. A clear and quantifiable link was established between the synoptic circulation patterns and the VRE potential and variability. It was found that the highest wind resource potential in South Africa occurs due to an extra-tropical cyclone, and the South Atlantic high-pressure system or the combination of the two systems. The areas of highest wind resource potential according to the study are along the west coast, over the south-western parts of the country and high-lying areas of the Western Cape Province and along the south coast. The highest solar resource potential occurs over the western interior of the country when there is predominantly a low-pressure trough over South Africa, accompanied by an approaching South Atlantic high-pressure system. Conversely, the South Indian high-pressure system leads to the lowest wind and solar resources. During a weak extra-tropical cyclone accompanied by the South Indian high-pressure system, the wind resource potential is also low and solar resource potential is low when there is an extra-tropical cyclone located over the country. VRE variability is relatively low when the VRE resource potential is high, but high when the VRE resource potential is low. A low-pressure trough over the western parts of the country, in combination with the South Indian high-pressure system over the eastern parts, results in high wind variability and low wind resource potential, especially over the western and southern interior of the country, but the solar resource potential is higher with relatively low solar variability, indicating that the solar power could be used to balance the variability caused by the wind. Understanding the relationship between wind and solar power variability and WRs and using this relationship to reduce variability would be beneficial to network planners, VRE plant developers, and network operators. This information can be used to ensure that wind and solar installations are located in optimal locations for power generation. It can also help network operators to understand when it is necessary to use the wind and solar power in combination to mitigate the variability in the power system. Recommendations include incorporating the different climate regions of South Africa into the study and investigating their influence on VRE resource potential and variability. The influence of mesoscale systems, such as thunderstorms and its possible effects on VRE could also be assessed. Further research could also be done to determine how the WRs can aid in the special deployment of VRE resources. AFRIKAANSE OPSOMMING: Die wêreld beweeg geleidelik weg van fossielbrandstowwe na veranderlike hernubare energie-(VHE) bronne soos wind- en sonkrag as gevolg van faktore soos klimaatsveranderingsbeleid, toenemende energie-onafhanklikheid van fossielbrandstowwe, en die vinnige prysdalings van hernubare energieopwekking. Suid-Afrika (SA) volg hierdie tendens, met wind en fotovoltaïese selle (PV) wat na verwagting 33% van elektrisiteit teen 2030 sal voorsien, gebaseer op die land se energiebeleid. Die energie wat deur wind en son voorsien word, is egter veranderlik, wat verskeie uitdagings vir elektrisiteitsnetwerke inhou. Op kort- tot mediumtermynskaal van ure tot dae, word windkragveranderlikheid tipies veroorsaak deur grootskaalse en langdurige weerpatrone (WP's). Die kwantifisering van die verhouding tussen atmosferiese sirkulasie en wind- en sonpotensiaal en -veranderlikheid is dus 'n voortgaande navorsingsveld. In die Suid-Afrikaanse konteks is daar relatief min navorsing in hierdie veld gedoen, ten spyte van die implikasies vir die balansering van vraag en aanbod. In hierdie studie word die hipotese getoets dat daar in die Suid-Afrikaanse streek 'n beduidende en meetbare verhouding tussen atmosferiese weerpatrone en die hulpbronpotensiaal en veranderlikheid van veranderlike hernubare energiehulpbronne bestaan. Hierdie verhouding maak dit moontlik om spesifieke WP's te identifiseer wat die sterkste invloed op VHE-hulpbronpotensiaal en -veranderlikheid het. Om die toetsing van die geformuleerde hipotese te ondersteun, is vyf navorsingsvrae geformuleer. Om hierdie vrae te beantwoord en uiteindelik die hipotese te bewys, is 'n oorsig gedoen van die uitdagings wat betrokke is by die integrasie van VHE in kragnetwerke. Dit het 'n omvattende oorsig van bestaande studies en gevestigde literatuur oor die verhouding tussen VHE en WP's opgelewer. Verskeie metodes wat voorgestel is om die veranderlikheid in hernubare energiehulpbronne te verminder, is ondersoek. Daarbenewens is weergroepe geanaliseer om windhulpbronpotensiaal en -veranderlikheid wat met sinoptieseskaalsirkulasie oor Suid-Afrika verbind is, te kwantifiseer. Die oorsig het die gebruik van selforganiserende kaarte (SOK's) geïdentifiseer as besonder geskik vir die klassifisering van atmosferiese toestande in hierdie studie. Hierdie oorsig het gedeeltelike tot die aanspreek van die navorsingshipotese bygedra. Verder is vasgestel dat beperkte navorsing gedoen is oor die spesifieke verhouding tussen VHE-veranderlikheid en WP's in Suid-Afrika. Om die geldigheid van die hipotese verder te ondersoek is 'n ontleding van die verhouding tussen WP's en die potensiaal en veranderlikheid van VHE-hulpbronne gedoen vir 'n 20-jaar tydperk, van 2001 tot 2020, met behulp van die ERA5-heranalisedatastelle vir wind, son en geopotensiaalhoogtes. Sinoptiese-skaalsirkulasie oor Suid-Afrika is geklassifiseer in 42 sirkulasie-grondvorme met behulp van SOK's. 'n Duidelike en meetbare verband is tussen die sinoptiese sirkulasiepatrone en die VHE-potensiaal en -veranderlikheid vasgestel. Daar is gevind dat die hoogste windhulpbronpotensiaal in Suid-Afrika voorkom as gevolg van 'n ekstra-tropiese sikloon, en die Suid-Atlantiese hoëdrukstelsel of die kombinasie van die twee stelsels. Die gebiede van hoogste windhulpbronpotensiaal volgens die studie, is langs die weskus, oor die suid-westelike dele van die land en hoogliggende gebiede van die WesKaapprovinsie en langs die suidkus. Die hoogste sonhulpbronpotensiaal kom voor oor die westelike binneland van die land wanneer daar hoofsaaklik 'n laedruklaag oor Suid-Afrika is, gepaardgaande met 'n naderende Suid-Atlantiese hoëdrukstelsel. Omgekeerd lei die SuidIndiese hoëdrukstelsel tot die laagste wind- en sonhulpbronne. Gedurende 'n swak ekstratropiese sikloon, vergesel deur die Suid-Indiese hoëdrukstelsel, is die windhulpbronpotensiaal ook laag en die sonhulpbronpotensiaal laag wanneer daar 'n ekstra-tropiese sikloon oor die land geleë is. VHE-veranderlikheid is relatief laag wanneer die VHE-hulpbronpotensiaal hoog is, maar hoog wanneer die VHE-hulpbronpotensiaal laag is. 'n Laedruklaag oor die westelike dele van die land, in kombinasie met die Suid-Indiese hoëdrukstelsel oor die oostelike dele, lei tot hoë windveranderlikheid en lae windhulpbronpotensiaal, veral oor die westelike en suidelike binneland van die land. Terselfdetyd is die sonhulpbronpotensiaal hoër met relatief lae sonveranderlikheid., Dit dui aan dat die sonkrag gebruik kan word om die veranderlikheid wat deur die wind veroorsaak word, te balanseer. Om die verhouding tussen wind- en sonkragveranderlikheid en WP's te verstaan en hierdie verhouding te gebruik om veranderlikheid te verminder, sou voordelig wees vir netwerkbeplanners, VHE-aanlegontwikkelaars en netwerkoperateurs. Hierdie inligting kan gebruik word om te verseker dat wind- en soninstallasies op optimale plekke vir kragopwekking geplaas word. Dit kan ook netwerkoperateurs help om te verstaan wanneer dit nodig is om die wind- en sonkrag in kombinasie te gebruik om die veranderlikheid in die kragstelsel te demp. Aanbevelings sluit in die insluiting van die verskillende klimaatstreke van Suid-Afrika in die studie en om hul invloed op VHE-hulpbronpotensiaal en -veranderlikheid te ondersoek. Die invloed van mesoskaalstelsels, soos donderstorms en moontlike effekte op VHE, kan ook geassesseer word. Verdere navorsing kan ook gedoen word om te bepaal hoe die WP's kan bydra tot die ruimtelike aanwending van VHE-hulpbronne. Masters 2025-06-05T09:45:41Z 2025-06-05T09:45:41Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132380 en Stellenbosch University 104 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Renewable energy sources -- South Africa Climatic changes -- South Africa Energy policy -- South Africa UCTD Van Aarde, Paulemari Emily The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title | The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title_full | The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title_fullStr | The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title_full_unstemmed | The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title_short | The relationship between weather regimes and variable renewable energy resource potential and variability in South Africa |
| title_sort | relationship between weather regimes and variable renewable energy resource potential and variability in south africa |
| topic | Renewable energy sources -- South Africa Climatic changes -- South Africa Energy policy -- South Africa UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132380 |
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