The pitfalls of hydroelectric power in drought-prone Africa

Dam spans deep river valley, with water gushing out and green-sided hills to either side

Alvaro Lara, former student on the MSc Climate Change, Management & Finance programme, considers Africa’s reliance on hydroelectric power, the impact of climate change on the water cycle and why current plans to invest in more hydroelectric projects may not be a route to energy security.

For much of 2017, one of the world’s least-developed countries, Malawi in south-east Africa, experienced intermittent blackouts as a result of low water levels at the country’s largest hydropower plant. But last December, the situation turned critical. Large areas of Malawi turned to complete darkness. The country – which gets 98% of its electricity from hydroelectric power – was left with just 150-megawatts (MWs) of power available out of the 300-MW it normally generates.

landscape with dry, cracked earth and no plants growing. people walking in distance
Image source: Africa CGTN

This power shortage sent Malawi, which has around 85% of its population of over 18 million people living in rural areas, into total disarray. The country’s power utility, Electricity Supply Company Of Malawi (ESCOM), imposed a schedule of rolling power outages across the country. Only one-third of the country received power at once and vast regions were subject to outages lasting up to 24 hours. As a result of the power cuts, businesses suffered severe economic consequences, and in some cases, the implications were far more serious. In December, there was public outcry following reports of premature babies dying in hospitals due to the absence of power for the incubators.

Malawi’s power crisis is not a one-off event

Over recent years, droughts and inconsistent rainfall across much of sub-Saharan Africa have exposed the vulnerability of power supply in the region.

Map of the Zambezi river, with national boundaries, showing location of hydroelectric dams
Map of the Zambezi river by Hel-hama [CC BY-SA 3.0 (], from Wikimedia Commons
  • In late 2015, the Tanzanian government was forced to shut down all its hydroelectric plants following droughts that dried up many of the country’s dams, or left them with dangerously low water levels. As a result, the country generated only 12% of the power it regularly consumed, leaving millions of people in the dark.
  • In 2016, the largest hydroelectric plant in sub-Saharan Africa, Mozambique’s Cahora Bassa, also found itself in trouble. Two years of drought conditions brought water levels to record lows, down to 34% of full dam capacity. The impact went well beyond Mozambique, as about two-thirds of power generated at the facility is sold to South Africa and Zimbabwe.
  • Also located on the Zambezi river is Zambia’s largest hydroelectric plant, the Kariba Kariba is located upstream of Cahora Bassa and supplies roughly 40% of Zambia’s power demand. Unsurprisingly, in the same year of Cahora Bassa’s record lows, power generation at Kariba fell by a whopping 75%.

The problem with hydroelectric power in Africa

Satellite map showing the location of river systems in Africa
Image source:

These events are a sign of future times. Hydroelectric power is, at its core, dependent on the hydrological cycle over a river basin. The hydrological cycle is, in-turn, driven by trends in climate; particularly consistency in rainfall and surface temperature.

The Intergovernmental Panel on Climate Change’s latest report on Impacts, Adaptation, and Vulnerability predicts that much of sub-Saharan Africa will experience considerably more severe and frequent droughts in the coming decades. The southwestern regions of Africaare projected to be at a high risk of severe droughts”. What is worrisome is that some of the most hydro-intensive river basins in Africa are found in these regions, including the Zambezi and the Congo river basins.

Reliance on hydroelectric power is high, dangerously high

Hydroelectric power dominates power generation in many African countries. In Ethiopia, Malawi, Mozambique, Namibia and Zambia hydroelectric power accounts for approximately 90% of all power generated. This is dangerous because it creates an over-reliance on hydroelectric resources. If the availability of these resources is ever at risk, there is no readily available source of back-up power. As seen in Malawi, without alternatives, fluctuations in rainfall and severe droughts can effectively shut down entire countries.

A recent study in the journal Nature Energy took this thinking a step further, looking at the susceptibility of power supply, not only from existing resources, but from all planned hydroelectric projects. The study found that the locations of new planned projects could put power supply at risk for large parts of Africa. This is because most planned hydroelectric projects will be concentrated in the same river basins. As a result, new and existing dams will rely on the same patterns of rainfall and, in-turn, be vulnerable to droughts at the same time.

Schematic map shows African river systems with dots indicating the location of current and proposed hydroelectric dams, which are buing built on the same rivers.
Existing hydropower dams in blue circles, planned (2030) in red; only dams over 50 MW are considered. Circles are sized according to installed generating capacity (MW). Boxes show boundaries used to calculate rainfall clusters. Shaded areas represent the main basins upstream of the hydropower dams. Details of all dams are listed in Supplementary Tables 15–18, Nature Energy volume 2, pages 946–953 (2017)

Image source: Nature Energy

Africa’s “more of the same” approach to hydro needs re-thinking

Despite this vulnerability of hydroelectric power, its use is likely to continue growing at a rapid pace in sub-Saharan Africa.

The most recent of these massive hydroelectric projects to become reality is the Grand Ethiopian Renaissance Dam (GERD). When it is completed, the 6,450-MW facility will become the largest hydroelectric project in Africa. The problem with Ethiopia’s GERD is its location on the Nile river, the source of life to hundreds of millions of people in the region, which is upstream of several existing large hydroelectric projects in Sudan and Egypt. Needless to say, Egypt or Sudan, whose economies are tightly linked to the Nile river, are not thrilled about the project, and rightly so. In its report, the IPCC highlights that “potential climate change impacts on the Nile Basin are of particular concern given the basin’s geopolitical and socioeconomic importance”. The Nile is not alone, scientists have also called for caution and further analysis ahead of new hydroelectric projects in the Zambezi, the Niger, and the Congo river basins.

African countries, perhaps among the world’s most vulnerable nations to climate change, may need to rethink their reliance on hydropower. Building more hydroelectric projects, in the same river basins, and subject to the same rainfall patterns and drought conditions, is akin to putting all your eggs in the same basket. Instead, governments should focus on strengthening the reliability of the existing power system, for example, by diversifying their (non-fossil fuel) power generation sources, and creating more robust transmission interconnections between regions, countries and river basins. The bottom-line is quite simple; building hydroelectric power plants in drought-prone areas of Africa will not guarantee energy security.

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Find out more

Read the research paper in Nature Energy: Hydropower plans in eastern and southern Africa increase risk of concurrent climate-related electricity supply disruption

Blog: Forget about power lines, Pay-As-You-Go is transforming Africa’s energy landscape

Blog: African smallholder farmers responding to an uncertain climate future

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