LACK of proper planning and poor management of the Kariba Dam has resulted in the current powercuts as both Zambia’s power utility, Zambia Electricity Supply Company (Zesco) and the Zimbabwe Electricity Supply Authority, through its subsidiary Zimbabwe Power Company (ZPC), burst their water usage ceiling by huge volumes resulting in an unprecedented decline of water levels in the dam.
The Zimbabwe Electricity and Distribution Company (ZETDC) has introduced a schedule of massive power cuts stretching up to 18 hours a day, attributing this development to low water levels at Kariba Dam, generation constraints at Hwange Power Station and limited imports. There are chances that ZETDC may introduce longer load-shedding hours if the crisis persists.
“Previously published winter load-shedding schedules have been reviewed in line with the increased shortfalls owing to the depressed generation levels at Kariba Power Station. In the event of further deterioration of the current available power supply, the level and duration of load- shedding may go beyond the advertising schedules,” ZETDC said in a statement.
The power utility has also blamed weather patterns, especially drought, as well as introducing ridiculous and unusual methods of preserving power supply, which includes the ban on electric geysers.
However, in a report titled Kariba Dam and power crisis: The cost of poor management, Greg Mills, the head of the Johannesburg-based Brenthurst Foundation, which has a global network of top analysts, says that excessive use of water by both Zesco and ZPC is the reason for the current major power crisis in Zimbabwe and Zambia.
Mills outlines that Zimbabwe has been heavily relying on Kariba for power generation because of its failure to rehabilitate its thermal power stations, while Zambia has also been relying on Kariba to meet the growing demand for electricity, largely because of the growth of its economy.
“Zimbabwe’s power demand is some 2 200MW (megawatts). Its supply is usually around two-thirds of this. In April 2015, for example, Harare, Bulawayo and Munyati stations were producing a combined output of 78MW against a capacity of 265MW. With problems afflicting Hwange Thermal Station, with an installed capacity of 920MW, pressure for continued production has been placed on Kariba to deliver close to its 750MW,” Mills explains in his report.
“Demand for electricity has grown very rapidly in Zambia as new customers have been connected to the grid. These have included residential, commercial, agricultural, industrial, and mining customers. Demand has increased from around 1 600MW in 2008 to about 2 200MW in 2015.”
He says as a result of the growing demand for electricity, both Zesco and ZPC, overstretched the limits of the water they draw from Kariba Dam.
“Kariba has been used to meet this growing demand, requiring more water to drive the turbines, pushing the volume of water use for generation to levels unsustainable by regular annual rainfall and inflows. Both Zesco and ZPC have been using more water than they are supposed to during 2015,” he says.
“Following the completion of the 360MW Kariba North Bank Expansion project in 2013/2014, Zesco has been generating a lot more electricity at Kariba than in previous years. The new turbines are being run much more than they were originally intended to. It seems that Zesco has been operating the intended peaking units much more than the planned three to four hours a day. This means they’ve needed to use more water, resulting in low reservoir level.”
Mills says as a result of the imprudent use of water in the Kariba Dam by both Zesco and ZPC, which was against stipulations by the regulator, Zambezi River Authority (ZRA), power cuts, which were supposed to be minimal, will be prolonged and severe.
He also says although ZRA reduced water allocations to Zesco and ZPC in March, the companies failed to comply with the order, exacerbating the situation.
“ZRA reduced the water allocations for Zesco and ZPC by 12% in March 2015. Instead of reducing their water use, both Zesco and ZPC substantially increased the amount of water used. Between March and June 2015, Zesco overused its water allocation by 39%, while ZPC overused by 16%,” he says.
“If the utilities complied with the allocations from ZRA, there would have been some load-shedding required beginning in March this year, but it would have been minor in comparison with current cuts. This would also have provided more time to source electricity imports and pursue other mitigation strategies prior to the situation becoming a crisis.”
Latest information gleaned from ZRA website this week confirms that high turbine outflows contributed to the low water levels in Kariba Dam, hence current power outages.
“The Kariba Lake was created and designed to operate between levels 475,50m and 488,50m with 0,70m freeboard at all times,” ZRA says on its website.
“The Lake levels continued dropping during the week under review. This is a result of low lake inflows coupled with high turbine outflows. The lake levels closed the week at 479,53m on 20th September 2015, which is 5,35m lower than the level recorded last year on the same date.”
Zambezi, on which Kariba Dam is built, is southern Africa’s longest trans-boundary river. It rises at 1 585 metres above sea level in north-western Zambia. The river flows for some 2 700km through plains, gorges, rapids and cataracts before spreading out in deltoid form as it enters the Indian Ocean in the east coast of Mozambique. It carries more than 75% of the mean annual runoff of the region’s interior, and drains more than 40% of the landmass.
The Zambezi River Basin is the fourth largest riven basin of Africa, after the Congo, the Nile and the Niger basins. The basin covers 1,3 million square kilometres spread over eight countries, namely Zambia (40,7%), Angola (18,2%), Zimbabwe (18), Mozambique (11,4%), Malawi (7,7%), Botswana (2,8%), Tanzania (2) and Namibia (1,2%). Almost 33% of the total population of the riparian countries lives in the basin.
Confederation of Zimbabwe Industries president Busisa Moyo said there is an urgent need to shake-up Zesa to address the worsening power crisis. Moyo said lack of planning by Zesa officials has exacerbated the power problems.
“Zesa needs to be restructured or the country will be paralysed. It’s time to act now,” Moyo said.
“Their current structure is too unwieldy and costly and there is a lack of transparency and lack of wide consultation. The water levels at Kariba should have been foreseen before opening the floodgates last year.”
Economist John Robertson said although the country has been unlucky in terms of rainfall, the failure to rehabilitate power infrastructure has worsened the power situation considerably.
“If Hwange Power Station was working properly this would have reduced load-shedding considerably,” he said.
Robertson said the lack of proper maintenance of the various power stations as well the failure to capacitate the National Railways of Zimbabwe has compounded the problem of prolonged load-shedding.
He said Zesa should have put in place contingency plans to help ameliorate the power crisis which is further damaging the country’s economy already hard hit by a plethora of challenges, among them, a crippling liquidity crunch, low capacity utilisation, company closures and massive job losses .
According to latest figures published on the ZPC website as of Wednesday, Hwange is currently generating 478 Megawatts (MW), Kariba 445 MW, Harare Power Station 30MW, Munyati 27MW and Bulawayo 18MW, translating to a mere 998MW for the whole country against a local total demand of 2 200MW.'