MCET NETWORK

SOUTH AFRICA | Energy Systems Research Group (ESRG) at the University of Cape Town

The Energy Systems Research Group (ESRG) in South Africa has developed the SATIMGE model to support the country’s energy transition, integrating the TIMES model with the eSAGE Computable General Equilibrium model. This tool provides comprehensive analyses of trade-offs for reducing reliance on coal, which currently supplies 90% of South Africa’s primary energy. SATIMGE is actively used in policy processes, including the 2030 and 2035 NDC updates. The team is enhancing the model’s power sector detail with hourly demand projections and spatial analyses to optimize renewable integration, making it a critical resource for sustainable planning.

About South Africa Team

The Energy Systems Research Group (ESRG) at the University of Cape Town specializes in analyzing and modeling energy systems to support sustainable development and informed policymaking. Focused on South Africa and the broader Southern African region, the group conducts interdisciplinary research on energy transitions, system integration, and policy impacts, aiming to guide investments and strategies in the energy sector.e.

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SATIMGE Model Adaptation for South Africa

SATIM, a full sector model combines a detailed view of South Africa’s Supply Sectors: Power, natural gas, coal, Hydrogen and Liquid Fuels, and the demand sectors: Household and Commercial Buildings, Industry, and Transport. The TIMES framework allows for optimization across all sectors, which is useful for identifying the least economically painful ways to allocate carbon space across sectors as the country increases its ambition and pace of transition into the future.

eSAGE helps to provide an internally consistent projection of growth given input/output relations in the economy and household income given assumptions about productivity growth and capital supply. It also provides projections of socio-economic indicators such as GDP, employment, household income and inequality as the transition, as described from a techno-economic way from SATIM, is imposed onto the economy e.g. transitioning away from coal for electricity production, process heat and a switch hydrogen in steel production and electrification across the board including in transport.

Open-Access Model

The Energy Systems Research Group (ESRG) develops and maintains a model called SATIMGE, which combines a full sector TIMES model (Hughes et al, 2021) and a Computable General Equilibrium Model (eSAGE, Alton et al, 2012). The model is combined with a simple waste and AFOLU model to have full coverage of the national GHG inventory. This makes SATIMGE a great tool for looking at various trade-offs faced by South Africa as it transitions away from Coal, which currently supplies 90% of total Primary Energy (ref EB).

Stakeholder Engagement

SATIMGE has recently been used in various policy processes such as the 2030 NDC for (PCC 2021), (PCC, 2022), (WB CCDR, 2022), NetZero for (PCC,2024), and is about to be used again for the next NDC update for 2035, which will be completed in 2025.

Research: Increasing the Temporal and Spatial Resolution of the Power Sector

However, SATIMGE, more specifically SATIM has been criticized for being too “coarse” on its characterization of the power sector. Under the work funded through the MCET project, the ESRG team is working on addressing this criticism by increasing the temporal and spatial resolution of the power sector in SATIM. This requires the following steps which are all in progress:

A way to downscale the demand projection coming from SATIMGE to hourly resolution to Eskom Supply Areas (Provinces + Hydra). This work is now completed and has been funded by SANEDI (Merven et al 2024).
A simplified characterization of the Transmission Network. The current network has been characterized and is shown in Figure 2. Characterization of network expansion is underway to determine likely grid constraints and investment requirements.
A more detailed spatial and temporal analysis of the RE resource for utility scale wind and solar is developed. Satellite-based reanalysis data estimating hourly RE generation tmieseries for zones across the country is combined with the most recently available hourly generation performance data for existing RE plants in South Africa (ref REDIS) to perform cross-validation and bias-correction. “RE.Ninja” data that is based on MERRA2 satellite data is used for wind and solar PV generation, and compared to the EU JRC “PVGIS” based on the SARAH2 and ERA5 satellites for PV (unavailable for wind). Single-axis tracking and fixed-tilt PV systems are modelled and bias-corrected separately.
Matched spatial zones across generation, transmission and demand, as well as RE capacity installation limits. The latest RE industry survey (Eskom 2024) is used to determine annual RE capacity installation rates and total capacity constraints for the different grid zones of South Africa. Eskom zonal “Supply Area” data is used to harmonize the spatial extents and matching of the transmission and generation zones for the model as well as the demand data that was downscaled previously.
An assessment of the amount of rooftop PV installed to date and potential for future installations in each market segment. This is work that is being done by Rufaro as part of her MSc.
The development of a more detailed TIMES model which would include the higher temporal and spatial resolution of the demand, supply and the interconnections. A simple prototype is already running which can handle hourly modelling, and various experiments are being conducted to evaluate the impact of including/excluding unit commitment features, running in dispatch only mode, running hourly vs using sampled days/weeks and strategies for exchanging data between the coarser version of SATIM (used with combined demand/supply optimization, and in capacity expansion mode) with the CGE link, and the more detailed SATIM-EL which could either be run in expansion planning mode (including Transmission expansion) or in dispatch only mode with operational constraints such as unit commitment to test expansion configurations proposed by SATIMGE. This more detailed representation would be potentially benchmarked using other tools such as Flextool 3.0, PyPsa-ZA and Plexos.
A VedaOnline dashboard is being developed for SATIM (see https://vedaonline.cloud/ModelPage.aspx[1]), and a similar one will be developed for SATIM-EL, which would allow users to access all underlying assumptions and results, and for specific groups of users, the possibility to also make changes and launch runs. Models will also be posted in public git repositories.

[1] A username must first be created. SATIMGE can be found under public models\brunom

References

Alton, T., Arndt, C., Davies, R., Hartley, F., Makrelov, K., Thurlow, J. and Ubogu, D., 2012. The economic implications of introducing carbon taxes in South Africa (No. 2012/46). WIDER working paper.
Eskom 2022, Eskom's Generation Connection Capacity Assessment of the 2022 Transmission Network (https://data.openup.org.za/gl/dataset/electricity-transmission-lines-ks5j-63iu/resource/9235c421-9ec1-4be8-a912-a6a5f55ab89a)
Eskom 2024, South African Renewable Energy Grid Survey 2024. https://www.ntcsa.co.za/south-africa-renewable-energy-grid-and-survey/
Hughes, A., Merven, B., McCall, B., Caetano, T., Hartley, F. and Ahjum, F., 2021. Evolution, Assumptions and Architecture of the South African Energy Systems Model SATIM. Energy Systems Research Group-Working Paper. http://www. epse. uct. ac. za/sites/default/files/image_tool/images/363/ESRG/Publications/2020 Evolution Assumptions and Architeture of the South African Energy Systems Model SATIM. Pdf
IRENA 2024. Advancements in continental power system planning for Africa, IRENA. (https://www.irena.org/-/media/Files/IRENA/Agency/Publication/2024/Jul/IRENA_Advancements_CMP_Africa_2024.pdf)
Merven B. Ireland, G. 2024. Demand Projection Model in Support of IRP Update 2023.
PCC 2021. South Africa’s NDC Targets for 2025 and 2030, Technical Report number 2, November 2021 (https://www.climatecommission.org.za/publications/south-africas-ndc-targets-for-2025-and-2030)
PCC 2022. South Africa’s Just Energy Transition Investment Plan (JET IP), 2022 (https://www.climatecommission.org.za/publications/sa-jet-ip)
PCC 2024. Analysis of Net Zero scenarios for South Africa using energy modelling techniques, forthcoming.
World Bank, 2022. Country Climate and Development Report (https://openknowledge.worldbank.org/entities/publication/c2ebae54-6812-51d3-ab72-08dd1431b873)

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