Our results show that countries currently under high-risk of water scarcity are expected to further increase their water use in the future due to fossil fuel consumption, leading to a vicious cycle. Under mitigation scenarios (2.0ºC, 1.5ºC), a reduction in demand in comparison to the reference scenario, coupled with the use of low-carbon technologies, leads to a decrease, but then an increase in water withdrawal and consumption, highlighting the role of nuclear, solar PV, hydropower and carbon capture with storage technologies (Supplementary Figure 2-7). Higher levels of electricity and gas trade are required to achieve lower emission limits, highlighting the role of transit countries and key net exporters. Nevertheless, it needs to be noted that higher levels of electricity exports in specific countries lead to higher levels of water withdrawal and consumption.
Future energy sector water requirements in the African continent
In the reference scenario, water withdrawals in Africa grew by almost eight times from 2015, reaching 159 billion cubic meters (bcm) in 2065. This increase corresponds to approximately 3% (2065) of the Total Renewable Water Resources (TRWR - 5,290bcm in 2015) in the continent27, assuming no changes in precipitation patterns due to climate change. This growth is mainly due to the penetration of high water-intensive technologies (coal, oil) and the increase in the hydropower share. Water consumption also increases by four times (187bcm) by 2065.
In the reference scenario, in the Northern Africa power pool (NAPP) and Central African power pool (CAPP), there is an increase in water consumption despite the transformation of the future energy mix to a higher share of renewables and the use of less water-intensive thermal general technologies. This transformation is due to the rapid increase in energy demands. On the other hand, in the East African Power Pool (EAPP) and South African Power Pool (SAPP), the increase in water consumption is explained by the adoption of water-intensive technologies. NAPP, EAPP and the Western African power pool (WAPP) experience an increase in their water withdrawals by 2065 while SAPP and CAPP experience a decrease, 13% and 61%, respectively. However, all power pools experience an increase in their water consumption ranging from 116% (NAPP) to 1576% (CAPP). Notably, countries with considerable hydropower potential (e.g., Angola, Cameroon, DRC, Ethiopia, Nigeria, Zambia) experience increased evaporative losses in the future (Supplementary Figure 47-49).
In the mitigation scenarios, overall water withdrawal also rise (2.0oC, 52bcm, TRWR 1%) (1.5oC, 85bcm, TRWR 2%) but to a lesser extent compared to the reference scenario (2.0oC, 67%), (1.5oC, 47%) by 2065. Also, decarbonizing further, the energy sector leads to an increase in water consumption of 282% (2.0oC) and 300% (1.5oC) by 2065, in Africa (Figure 2). These results support the message that pathways towards decarbonization of the energy sector in Africa may lead to higher water withdrawal and water consumption. This observation highlights the significant role of clean technologies with a low water footprint versus hydropower with integrated water resources management that secures water for other purposes (e.g., agriculture, municipal services). It is particularly relevant in NAPP and WAPP, which have set ambitious renewable energy targets. However, the projected nuclear investments in Egypt, Morocco, Chad, Guinea, Gabon, Uganda, Nigeria, Benin, Côte D Ivoire, Ghana, Senegal, Mali, increase water withdrawals in the above scenarios.
The role of inter-regional trades, national mega-projects and transit countries
Fossil-fuel reserves, renewable potential and water resources are unevenly distributed in Africa. The results show how trade among African countries could influence water resources management, decrease electricity generation costs and lower emission levels across the scenarios. The largest electricity net exporters by 2065 are Kenya, South Africa and Sudan, while the main net importers are Uganda, Burkina Faso and Mali. The high potential for renewables in the EAPP makes the region the largest net exporter of electricity. A notable finding of this study is the identification of some countries as transit-traders such as Egypt, Sudan, South Africa and Tanzania (Figure 3). Indicatively, under the reference scenario, Egypt imports 659TWh (94%) of its cumulative electricity imports from Sudan. In parallel, Egypt exports approximately 1194TWh (96%) of its cumulative electricity exports (2015-2065) to Asia. In parallel, 64TWh or 15% of Sudan's total electricity exports are derived from imports of electricity generated in Ethiopia. Increased electricity trade enables optimized system operation and typically results in cheaper electricity costs and lower emission levels. However, for the exporting countries, there are consequences for their national water needs. Specifically, the potential implementation of the Grand Inga project in the Democratic Republic of Congo, together with trade links, could increase the electricity exports to neighboring countries and displace part of their fossil-fuel based generation. Zimbabwe is one of the countries which undergo a transformation from net exporter in the reference scenario to a net importer in the decarbonization scenarios to reduce its fossil fuel-based generation capacity, importing on average 14 TWh of electricity annually.
These results highlight the importance of an enhanced electricity trading scheme on the continent to reduce greenhouse gas emissions and system costs. Nevertheless, this could come at the expense of increasing the water consumption in the main electricity exporter countries, particularly Ethiopia, Guinea, Liberia, Sudan, South Africa, putting them at risk of water shortages. However, countries such as Ghana, which increase their electricity net imports in all scenarios, experience a concurrent decrease in their water requirements. In short, investment decisions in large hydro-electricity generation projects cannot be separated from water resource management and electricity trade and require regional coordination across countries, tailored to the local geopolitical and topological realities.
Also, specific gas pipeline projects (e.g., West African, Trans-Saharan) could change certain countries (Algeria, Mozambique, Nigeria) to become energy hub exporters assisting their neighboring countries to transform their energy sector.
Transformation of the energy system
The evolution of the energy mix of a core group of fossil fuel resource-rich countries play an essential role in African greenhouse gas emissions. For example, South Africa and Lesotho extract most of the continent's final coal consumption. Nigeria and Egypt are large consumers of oil products. Algeria, South Africa, Nigeria, Egypt and the Democratic Republic of Congo will consume most of the continent's natural gas, in final energy terms. The analysis of how the final energy consumption evolves among the scenarios can be found in Supplementary Information.
In the reference scenario, the total African primary energy supply more than doubles compared to 2015, reaching 1853Mtoe by 2065. While the share of fossil fuels increases over the years (64%), renewables experience a gradual decrease, eventually reaching 36% of the total primary supply by 2065 (Figure 4). Without a carbon constraint, coal, as the cheapest source of electricity, constitutes most of the continent's primary energy supply, followed by oil and biomass. Nuclear power disappears from the electricity supply system by 2065. The WAPP stands out as the most significant energy supplier (35%) in Africa, followed by EAPP (28%), SAPP (19%), NAPP (11%) and CAPP (7%) in 2065. WAPP is also the largest supplier (37%) of fossil fuels and renewables (32%) in the continent in 2065.
However, in the 2.0oC and 1.5oC scenarios, due to the relatively lower final energy demand, African countries increase their 2065 total primary energy supply by only 50% and 31%, respectively, in comparison to 2015. Moreover, the primary supply of fossil fuels in those two scenarios declines dramatically throughout the years, reaching 27% and 8% by 2065. On the contrary, renewables increase by 64% and 72%, respectively, by 2065 (Figure 4).
As natural gas reserves are scattered among nations, the role of natural gas trade through pipelines and LNG terminals is key to decarbonize the African energy system. Countries with significant natural gas reserves, such as Algeria, Nigeria, or Mozambique, increase their natural gas exports significantly to reduce the consumption of more polluting fossil fuels in the continent. In particular, Mozambique increases its gas exports to South Africa for replacing coal in the power sector with natural gas.
Under the mitigation scenarios, natural gas supply to Europe through the Northern African countries gradually declines, which is in line with Europe's aim to become a climate-neutral continent by 2050. The Western African power pool and specifically Nigeria, will be the leading natural gas supplier in the African continent. Several coastal countries (Côte D Ivoire, Ghana, Morocco, Sudan, Senegal, Tunisia, Tanzania and South Africa) increase their LNG imports. This increase in imports leads to lower emission limits by replacing the above countries' fossil fuel capacity in the power sector as well as decreasing their water requirements.
Evolution of the electricity supply sector
In the reference scenario, the overall generation capacity in Africa rises ten-fold from 181GW (2015) to 1863GW (2065). The share of renewables increases from 19% (2015) to 78% (2065), while the percentage of thermoelectric capacity decreases from 82% (2015) to 22% (2065). Hydropower was the dominant renewable source in 2015. However, as the costs of renewable (solar, wind) technologies are declining throughout the years, solar photovoltaic (PV) technologies represent most of the continent's installed capacity by 2065. In the decarbonization scenarios, the percentage of renewables reach even higher figures 86% (2.0oC) and 87% (1.5oC) in 2065 and resulting in generation capacities of 1843GW (2.0oC) and 1833GW (1.5oC).
In the reference scenario, CAPP is electrified almost exclusively by renewables (94% of installed capacity) in 2065. At the same time, EAPP hosts most of the continent's renewable installed capacity (427GW) and NAPP experiences the highest increase (46 fold) in all scenarios. As expected, CAPP becomes the leading hydropower producer due to the Democratic Republic of Congo and EAPP (Sudan, Uganda) continues to invest in hydropower. Concentrated Solar Power (CSP) technologies are limited to NAPP (Morocco) and EAPP (Egypt) and geothermal to EAPP (Kenya, Ethiopia). In mitigation scenarios, to achieve the emission targets, carbon capture and storage (CCS) technologies and nuclear power plants are required along with the replacement of coal-based power plants by natural gas.
Nevertheless, to encourage decarbonization of the energy sector, the technological maturity of CCS technologies needs to be considered along with the feasibility of nuclear energy in the African context. Socio-economic concerns of nuclear power exceed the scope of this analysis50. In decarbonization scenarios, WAPP (Nigeria, Ghana), Egypt and Morocco present most of the continent's nuclear capacity in the future, mainly replacing thermal capacity. In the same scenarios, SAPP (Angola, South Africa, Zambia, Zimbabwe) invests significantly in biomass with CCS technologies while Egypt invests in natural gas with CCS.
Our results show that to decarbonize the energy sector, the gas-fired power generation technologies, along with the penetration of renewables, CCS and nuclear technologies, replace coal-based power generation. In the reference scenario, electricity generation in Africa increases from 64Mtoe (2015) to 510Mtoe (2065). Renewables gradually penetrate the electricity mix reaching 57% (2065) from 18% in 2015 and 75% in both the 2.0oC and 1.5oC scenarios. Solar PV technologies followed by hydropower are the dominant power generation renewables in the future. In the reference scenario, coal-based power generation is the primary thermal power source in the long-term instead of natural gas in the decarbonization scenarios where thermoelectric generation is lower than in the reference scenario (45% in 2065), specifically 34% (2.0oC) and 31% (1.5oC) by 2065.
Also, technologies combining CCS constitute 9% (2.0oC) and 8% (1.5oC) of the total electricity generation by 2065. An insight among the scenarios is that the coal-based power generation regions, SAPP and WAPP, replace their generation significantly by wind and solar in the first case while in the second case with natural gas and nuclear.
In the reference scenario, the total system costs associated with the energy sector in Africa are estimated at USD2015 24,520 trillion. Under the mitigation scenarios, the total costs are lower by 29% (2.0oC) and 54% (1.5oC) compared to the reference scenario, for the period 2015-2065. In the mitigation scenarios, the penetration of renewable technologies leads to fuel supply savings of 32% (2.0oC) and 53% (1.5oC) compared to the reference scenario (Figure 5). As expected, mitigation scenarios are capital-intensive and the capital investments in the power sector are higher by approximately 9% (2.0oC) and 19% (1.5oC) compared to the reference scenario (Figure 5). Despite that, the significantly lower operating expenses, show that decarbonization options, which include energy efficiency measures, are beyond any doubt the cost-efficient pathways. This indicates that increasing the ambition of climate targets results in lower cumulative costs. All scenarios assume universal access to clean energy by 2065, hence the high investment projections in 2030-2065.
Developing strategies for the African continent should, therefore, prioritize sustainable technologies, demand-side management and set ambitious targets. This also applies to oil-producing countries of the continent (e.g., Algeria, Tunisia) since they are expected to profit from electricity trading leading to savings on their total fuel costs by 48% (2.0oC) / 46% (1.5oC) and power system costs by 28% (2.0oC) / 7% (2.0oC) compared to the reference scenario, improving in parallel their water productivity by approximately 50%.