Brace for crippling power cuts


The country’s integrated power generation and supply company ZESA Holdings is set to implement a painful load-shedding for the first time in nearly four years after the Zambezi River Authority (ZRA), a joint venture outfit owned by the governments of Zimbabwe and Zambia responsible for the management of water in the Zambezi basin, was forced to reduced water allocation for power generation at the Kariba Dam due to a sharp drop in water level.

The situation has also been exacerbated by the deteriorating coal supply at Hwange Power Station, the country’s largest coal-fired power plant.  The development is coming at a time when ZESA is battling machine breakdown at its four thermal power stations in Hwange, Harare, Munyati and Bulawayo. The small thermal power stations were commissioned between 1946 and 1958 and have since reached their design life, which is 25 years.

Most of the plants require either life extension measures or complete replacement. Consequently, their generation capacity has seriously declined.

Rolling power cuts, which were last experienced in December 2015, mean industries and households will be subjected to long hours of crippling outages throughout the country daily.

Business Times can report that ZESA made the load-shedding request last month and government has since given thumbs up to the power utility’s proposal. This means electricity consumers should now brace for the load-shedding, which will cause serious repercussions on the recovery of the productive sectors of the economy such as mining, manufacturing, agriculture and tourism, which government wants to drive the country’s economic recovery.

In a letter seen by this newspaper this week, Energy and Power Development permanent secretary Gloria Magombo wrote to ZESA Holdings unit, the Zimbabwe Electricity Transmission and Distribution Company (ZETDC)’s acting managing director Ralph Katsande, saying the ministry okayed its proposal to start load-shedding.

She asked ZESA to provide the proposed load-shedding schedule.

“The ministry is in receipt of your letter dated March 14 2019 on the (load-shedding) subject matter,” Magombo said.

“In the letter, ZETDC, was advising the ministry on the necessity to implement a load-shedding program in cognizance of the reduction in water allocation by Zambezi River Authority at Kariba Power Station and also the deteriorating coal supply situation at Hwange Power Station.”

She added: “The ministry concurs with ZETDC’s proposal to implement a load-shedding program in compliance with ZRA and also to mitigate the impact of coal supplies situation. To this end, ZETDC, is being requested to submit the proposed load-shedding schedule to the ministry for its perusal before implementation,’ Magombo said.

Analysts who spoke to Business Times yesterday said the move will undermine business confidence. They highlighted that unstable power supplies will cause companies to incur heavy losses as some processes will be interrupted thereby affecting the quality of products.

Some processes will also be delayed or aborted resulting in failure to meet deadlines and targets for many companies.

Chamber of Mines of Zimbabwe chief executive officer, Isaac Kwesu said load-shedding will serious r impact on the mining sector.

 “Our hope is that the little available energy will be spared for critical sectors such as mining,” Kwesu said.

“You cannot switch mining off for safety preservation.  Apart from production depending on electricity, we need to guarantee safety of workers. We are appealing to ZESA to be prioritized. We also have dedicated lines for miners who are ring-fenced. It is our hope and we will engage ZESA to ensure that the ring-fencing contracts are respected,” Kwesu added.

The ZRA, which was established in 1987 as a successor to the Central African Power Corporation, is mandated to manage and harness the Zambezi River waters. It also maintains the Kariba Dam Complex which comprises the dam wall, Lake Kariba water storage reservoir and other associated ancillary facilities such as lake levels and river in-flows monitoring equipment.

Through the rule curve, ZRA determines water levels, that’s the highest and lowest tolerable level, to which the Kariba Dam reservoir may provide firm loads of water for power generation.

Recently, ZRA reduced the water allocation for power generation at the Kariba Dam to 36 billion cubic metres for 2019 from 38 billion cubic metres last year, a drop of 56%.

This means, the Zimbabwe Power Company (ZPC), a generating unit of ZESA Holdings, and the Zambia Electricity Supply Corporation (ZESCO) which share the water resource from Kariba Dam for power generation for their power stations on the southern and northern banks of the Kariba Dam respectively, will only be able to utilize 18 billion cubic metres of water each to generate electricity. This means they will only be able to generate about 500 megawatts (MW) from the previous 1000MW on average, due to plummeting water levels.

The plant has been producing relatively cheaper and reliable electricity for the country but is now unlikely to perform to its optimal due to reduced usage of water.  It has been supplying electricity at an average cost of $0,02 per kilowatt hour (kW/h) while the four thermal power plants at Hwange, Harare, Munyati and Bulawayo have been generating  power at an average cost of between $0,08 per kW/hand $0,16 per kW/h.

Failure to adhere to ZRA directive will result in steeped drawing down of the live storage of water. Continuing generating over 1000MW of electricity would result the lake falling below the minimum drawdown level of 474,5 metres  above sea level, a situation which could lead  to a possible  shut down of the power station. Should water inflows into the dam fail to improve, the situation could be grave, as crippling power cuts would undermine the competitiveness of local industries and also worsen the low productivity levels in the manufacturing sector.

The lake is currently about five metres above the minimum operating level when it should be eight metres, according to ZRA.

It is understood that each machine, when running, requires a massive 150 cubic metres per second of water, which translates to a stunning 1 200 cubic metres of water per second when all the eight units are running.

According to the rule curve, if things are normal, Kariba Dam’s water level starts to go up in January, a situation attributed to low local in-flows.

Zimbabwe contributes about 20 percent of the inflows into Lake Kariba.

Munyati River feeds Sanyati River, which then supplies water water into the lake, but those rivers are harfly flowing due to poor rainy season across Zimbabwe.

The other source is Gwai River. Again it is not flowing. This means there have not been significant inflows into the lake.

From the other sources in Zambia, Angola and the Democratic Republic of Congo, the inflow into the lake normally comes in March or May. But, currently, the inflows are also low.

Zimbabwe used to draw about 1050 MW of electricity from Kariba South Hydroelectric Power Station. But, this has been slashed to about 500MW, owing to dwindling water levels at Kariba Dam-occasioned by a drought that ravaged the 2018/2019 farming season.

While reduction of water allocation is meant to ensure that there is enough resource to sustain power generation until the onset of the 2019/2020 rainfall season, it would worsen the power supply situation in the country at a time Zimbabwe is battling machine breakdown at its hydro power plants.

A poor rain-flow season implies reduced river water in-flows into Lake Kariba, which in turn reduces water available for power generation. This will result in low electricity generation at Kariba. The situation is likely to continue as the lower catchment rivers are particularly dry by August or September of every year.

Kariba South Hydro Power Station had remained Zimbabwe’s biggest generator of electricity.

Related Articles

Leave a Reply

Back to top button