Background, challenges, and context

Climate change is expected to significantly impact electricity systems in the Southern African Power Pool (SAPP) – which comprises 12 countries (Angola, Botswana, Democratic Republic of the Congo, Eswatini, Lesotho, Mozambique, Malawi, Namibia, South Africa, Tanzania, Zambia, and Zimbabwe) and accounts for 40% of Africa’s electricity demand, with demand anticipated to double by 2040.

Large hydropower, which continues to be promoted as a cost-effective and low-carbon source of dispatchable electricity in Africa, is especially vulnerable to climate change. Eight of the 12 SAPP countries are dependent on hydropower for more than half of their electricity generation, and several additional hydropower projects are under construction or proposed. But the Southern African region is likely to experience higher temperatures and lower precipitation in the future, which is expected to severely affect electricity generation from hydropower.

Climate change is also expected to have an impact on wind generation (because of changing wind patterns) and solar generation (with high temperatures and changing cloud patterns decreasing efficiencies). On the demand side, rising temperatures are likely to increase electricity demand due to the greater adoption and increased use of cooling appliances.

Most climate change research on the Southern African region and elsewhere has mainly focused on the impacts on only one or a few aspects of electricity systems, and has not comprehensively incorporated these impacts into electricity system planning and operations.

Furthermore, the development of hydropower, wind, and solar infrastructure may directly conflict with biodiversity and ecosystems, as well as negatively impacting local communities.

Hydropower development has significant potential negative social and environmental impacts (historically underestimated in power sector planning). Upstream of retention dams, the flooding of natural habitats can result in loss of biodiversity, the involuntary displacement of people, and loss of cultural property. Downstream, variations, especially reductions in the hydrological flow, can undermine ecosystem services, cause loss of biodiversity, negatively affect water quality, and impact water availability for other sectors.

Wind, solar, and battery technologies have their own technical, environmental, and social challenges too. Weather-dependent renewable sources, especially wind and solar, are variable and uncertain, complicating the planning and operation of future low-carbon electricity systems. Large battery storage can help to manage variability, but the scale-up of batteries, especially of Lithium ion-based technologies, pose significant challenges associated with mining and recycling. Large-scale wind and solar power plants also require a significant amount of land.

If not addressed, the conflicts arising from hydropower, wind, and solar developments will likely result in project delays and cost overruns, and require mitigation and compensation costs that would affect the feasibility of new energy infrastructure. Understanding whether and how much of the proposed and potential renewable energy resources are environmentally and socially compatible is critical for designing sustainable low-carbon pathways and planning renewable energy infrastructure.

Research overview and objectives

The study examined the potential impacts of climate change on electricity demand, hydropower energy availability, and thermal and solar power generation in the Southern African region’s electricity system from 2020 to 2045.

In addition, wind, solar, and hydropower resources in the SAPP were characterised under different sets of environmental and social criteria. Least-cost electricity infrastructure investments under different sets of socio-environmental constraints and carbon emission targets were identified, and the costs of imposing increasing environmental and social constraints on low-carbon pathways for Southern Africa’s electricity system were evaluated.

Research methodology

The team compared energy generation, costs, and carbon emissions in a base scenario that assumed historical weather conditions with four future climate scenarios from the Coupled Model Intercomparison Project Phase 6 (CMIP 6). CMIP is an initiative that brings together multiple climate models from different modelling groups around the world.

Two of the scenarios selected in this study represented more overall drying, whereas the other two represented less overall drying due to climate change in the main subregions of Southern Africa, but in each scenario, precipitation varied across the region. For each climate scenario, average, dry, and wet precipitation conditions were selected over a 20-year period (1997-2016 for historical and 2036-2055 for climate change conditions). They also represented distinct combinations of plausible future changes in temperatures and precipitation patterns in Southern Africa. The changes in patterns were used to drive changes in electricity demand, hydropower energy availability, thermal power plant availability, and solar photovoltaic (PV) generation efficiencies from 2020 to 2045.

The team evaluated the effects of these demand and supply changes using a detailed electricity system planning and operations model. First, the team developed cost-optimal investments in generation, storage, and transmission assets assuming historical weather data. Second, the team fixed these investments but applied the demand and supply changes to the model and examined the cost, emissions, and demand curtailment effects of these changes until 2045. Third, to understand the economic implications of incorporating the effects of climate change within electricity planning, cost-optimal investments in electricity infrastructure were developed for each of the climate scenarios. These electricity pathways for Southern Africa were examined with and without imposing a low-carbon emission target.

The open-source power system modelling platform GridPath was used to identify cost-optimal electricity infrastructure investments in the SAPP for each of the scenarios. Utilising temporal and spatially explicit demand, wind, solar, and hydro resource data along with various economic and technical constraints, GridPath identified cost-effective deployment of conventional and renewable generators, storage, and transmission lines by co-optimising power system operations and infrastructure investments. Six investment periods – 2020, 2025, 2030, 2035, 2040, and 2045 – were modelled – each representing five years.

To study biodiversity and social impacts, the team created socio-environmentally constrained scenarios by screening solar, wind, and hydropower techno-economic potential using protected areas, sensitivity areas for focal species, forested areas, free-flowing rivers, and select agricultural lands. The Multi-criteria Analysis for Planning Renewable Energy (MapRE) spatial energy systems modelling framework (which allows stakeholders to weight multiple renewable energy siting criteria e.g. generation cost, distance to transmission lines and load centres, and possible environmental impact – and examine their trade-offs), was adapted to identify suitable wind and solar PV sites for the environmental and social impact scenarios across the 12 SAPP countries. Inundation extents of proposed hydropower reservoirs were mapped using a digital elevation model and then intersected with socio-environmental spatial datasets for screening the projects.

After screening, suitable solar, wind, and hydropower projects were fed into GridPath to create optimal electricity generation portfolios and identify the renewable energy and hydropower plants that would remain cost-competitive under each scenario. To explore the implications of reaching conservation and climate objectives concurrently, the team compared scenarios that do and do not cap greenhouse gas emissions at 50% of current emissions by 2040.

Research results, key messages, and recommendations

Climate change impacts

• Under climate change conditions, rising temperatures drive increases in electricity demand. Across Southern Africa, annual electricity demand is expected to increase by 2-5% because of higher temperatures in 2045 compared to demand under historical weather conditions.

• Across all climate scenarios, electricity demand increases mainly in the summer months.

• The results for all climate scenarios indicate that climate change is likely to reduce future streamflow, and thus hydropower production, particularly during the wet season, in almost all river basins – eight were modelled – the Zambezi, Congo, Kwanza, Cunene, Rufiji, Orange, Limpopo, and Buzi – which encompass more than 90% of the SAPP's total installed (13 GW) and projected (59 GW) hydropower capacity. Average annual hydropower generation reduces across all climate scenarios by 2-8%.

• The annual hydropower production for the entire SAPP region is likely to be less than the historical production in almost each of the future years between 2036-2055 across all climate scenarios. This suggests a strong likelihood of climate change impacting Southern African hydropower systems (as reported in several previous studies).

• If the effects of climate change are not incorporated in electricity planning (i.e. infrastructure investments are based on historical weather conditions), system costs increase by up to 3% and carbon emissions by up to 13% by 2045.

• More importantly, up to 4% of demand is curtailed because of a lack of availability of generation capacity.

• Incorporating climate change impacts in electricity system planning increases costs by up to 4% – this is similar to scenarios that do not incorporate climate change impacts in planning, but avoids demand curtailment.

• If electricity infrastructure is planned under a low-carbon cap of 100 MtCO2 by 2045, the impacts on system costs and demand curtailment are less because climate change impacts on renewable energy generation are expected to be much lower than on thermal power generation.

• The modest system cost increases show that policy and decision makers should incorporate climate change impacts in electricity system planning to maintain system reliability.

Biodiversity and social impacts

• Significant potential for wind and solar remains after excluding areas with environmental and social importance.

• About 60% of planned or proposed hydropower projects face potential socio-environmental conflicts.

• The optimal mix of generation technologies with socio-environmental protections results in more wind, solar, and battery capacity but a reduction in hydropower capacity compared to scenarios without protections.

• Less hydropower will be developed than announced plans under any modelled scenario, given relative development costs and socio-environmental considerations. Even under a high carbon cap (50% emission reductions by 2040 compared to 2020), the total amount of cost-competitive hydropower does not exceed 55% of planned or proposed hydropower capacity – and is only 25% when considering socio-environmental protections.

• The combination of carbon target and land use protections results in overall electricity system cost increases of 6-13%.

• Electricity system cost impacts vary across countries within the region depending on which hydropower and renewable energy projects are excluded from consideration.

• Improving electricity trade and transmission infrastructure could mitigate costs and impacts on consumers.

• These findings highlight an opportunity for the international community to support the development of environmentally and socially sustainable low-carbon pathways at relatively modest cost. This would ensure climate compatible, socio-environmentally sustainable economic development in the SAPP region.

The team engaged with policy makers and other stakeholders throughout the project. The findings have been communicated through a range of activities, including presentations to the sub-committee of senior energy officials from Southern African Development Community (SADC) member states; the SADC Centre for Renewable Energy and Energy Efficiency (SACREEE) Board (consisting of ministers from SADC member states); and technical and management staff from electricity regulators in the SADC region at the Regional Electricity Regulators Association of Southern Africa (RERA) annual conference. The team organised multiple online workshops, to both present the results of this study as well as to train stakeholders in the open-source tools and models developed in the study.

Local partners

Southern African Development Community (SADC) Centre for Renewable Energy and Energy Efficiency (SACREEE)

Regional Electricity Regulators Association of Southern Africa (RERA) 

Southern African Power Pool (SAPP)

University of Cape Town, Climate System Analysis Group