In Eastern and Southern Africa, droughts threaten the power system

Every day, electricity is cut off for several hours in Tanzania, Zimbabwe and Zambia due to low water levels from hydraulic dams.

Source LeMonde Afrique | By Marion Douet (Nairobi, correspondence), translated by Google

Posted on December 23, 2022 at 7:00 pm, updated on December 25, 2022 at 8:12 pm

On the borders of Zimbabwe and Zambia, a huge concrete arch has risen since the late 1950s over the turbulent waters of the Zambezi River. The Kariba Dam, with a total capacity of around 2,000 megawatts (MW), is still today one of the largest hydropower plants in Africa and alone provides 70% of the electricity consumed in Zimbabwe. . But it is currently dry: its gigantic reservoir is only 3% full due to repeated droughts.

“Having no other choice” , Harare has been carrying out massive power cuts since the beginning of December, up to nineteen hours a day, in a country already in the grip of a dizzying economic crisis. Residents of the capital told Agence France-Presse that they got up in the middle of the night to take advantage of the rare hours of electricity available and thus charge their telephones, or iron a shirt. On the other side of the river, Zambia, which also operates Kariba, has also announced load shedding.

Further north, in Tanzania, the low water level of the dams, coupled with maintenance problems, led the authorities to the same drastic decisions. "Right now, they cut the power between six and eight hours a day, sometimes twelve ," testifies Aviti Thadei Mushi, professor in the department of electrical engineering at the University of Dar es Salaam.

cheapest resource

The economic capital, rather preserved from “rationing” in normal times, is particularly affected, says the university, sometimes unable to give his lessons in amphitheaters deprived of current. “In homes, if the fridge has no electricity for eight hours, all that food goes in the trash. People complain a lot,” he adds . More broadly, the whole economy is affected. “Take the barber who runs a small salon down the street. Without electricity, he can't do anything ,” observes Mr. Mushi.

“Recent scientific studies have shown that the variability between extremely wet and dry years will increase across East Africa”

David Mwangi, a Kenyan expert who worked for the Power Africa electricity access program, points out that such cuts heavily affect industries. Admittedly, large factories are equipped with generators, but they are diesel-intensive. Their prolonged use is much more expensive than grid electricity and drives up production costs. “Smaller industries, which do not necessarily have generators, will have to stop production or reduce the number of hours worked,” he adds.

Many countries in Eastern and Southern Africa are very dependent on hydroelectricity, sometimes over 90% of the electricity mix, as in Ethiopia or Lesotho. We took advantage of large rivers and a rugged topography, in particular by the fault of the Rift, to bet on this constant and reliable energy. "Historically, it has been the cheapest energy resource, so very attractive to countries in the region ," adds Sebastian Sterl, an energy expert based in Addis Ababa for the World Resources Institute, a think tank working on the environment.

But global warming and its recurring drought episodes are destabilizing this system. "Several recent scientific studies have shown that the variability between extremely wet and extremely dry years will increase across East Africa" ​​, he continues, adding that this observation is for the moment less "clear" in other regions . African. The expert pleads for a diversification of energy sources, “in order to take over if hydro turns out to be unavailable”.

This is the case in Kenya, where hydropower now represents only around 30% of installed capacity, thanks in particular to the massive expansion of geothermal energy. Water levels there are currently low, but the economic locomotive of East Africa is not currently suffering from cuts linked to drought, the intensity of which has not yet been seen for forty years. “We have optimized the use of dams by reducing their use and increasing that of geothermal energy, so that Kenyans are not affected” , welcomes a spokesperson for the national electrician, KenGen. Even the few – and expensive – oil-fired power stations in the country remain little used for the moment, he assures us, which avoids increasing the electricity bill in a context of record inflation.

national pride

For Sebastian Sterl, the consequences of global warming do not necessarily sound the death knell for hydroelectricity in the region. First of all, some areas like Uganda or eastern Democratic Republic of Congo (DRC) remain very humid. Elsewhere, dams are complementary to other energies, particularly renewable ones: thus, in Ethiopia, sunshine and the blowing of the wind are at their peak during the dry season, when the hydrology is at its lowest. And vice versa in the rainy season.

The country is also completing the Renaissance megadam, the largest in Africa, after years of Herculean work on the Blue Nile. The work, a national pride at the heart of strong tensions with its neighbors, Sudan and Egypt, must exceed 5,000 MW, the equivalent of at least five standard nuclear reactors. The filling of its huge reservoir, which has already begun, will take two to three years to reach its maximum, notes Mr. Sterl. "Depending on the rainfall," he says.

Marion Douet (Nairobi, correspondence)