Zambezi River Authority increases water for power generation
Kariba dam can carry up to 65 billion cubic metres of water.
THE Zambezi River Authority (ZRA), which administers the Zambezi River and the use of Lake Kariba on behalf of the governments of Zimbabwe and Zambia, will next year increase water allocation for power generation from 20 billion cubic metres to 30 billion cubic metres.
This is due to expectations that there will be good rains this season.
This means that both the Zimbabwe Power Company (ZPC) which operates the Kariba South Power Station, and the Zambia Electricity Supply Authority (ZESCO)’s Kariba North Bank Power Station, will have an allocation of 15 billion cubic metres of water each for power generation next year.
At full capacity, Kariba dam has about 65 billion cubic metres of water.
ZRA chief executive officer, Munyaradzi Munodawafa, confirmed the development this week.
“Indeed we have already reviewed the water allocation for next year and each utility has been allocated 15 billion cubic metres of water. The next review will be in the first quarter of 2017,” Munodawafa told this newspaper.
He added: “This year there is no change and the utilities will need to adhere to this year’s allocation of 10 billion cubic metres each.”
“The reasons for increasing water allocation was based on the forecast. We anticipate that we are going to receive normal to above rainfall in the coming rainy season. Therefore, we anticipate that we will get about 35 billion cubic metres of water next year,” said Munodawafa.
Munodawafa, however, did not disclose if ZPC and ZESCO would be allowed to adjust upwards their hydropower generation.
Currently, Kariba South Power Station is generating 285 megawatts (MW) of electricity, out of a total installed capacity of 750MW, daily.
Zimbabwe’s northern neighbour Zambia, is at present generating about 275MW from an average of around 1 080MW.
ZRA, which was established in 1987 as a successor to the Central African Power Corporation, manages and harnesses 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, the ZRA determines water levels — that is the highest and lowest tolerable levels — to which the Kariba dam reservoir may provide firm loads of water for power generation to ZPC and ZESCO, the two power utilities which share the water resource for power generation.
In May last year, ZRA first reduced water allocation to the two power utilities from 45 billion cubic metres to 33 billion cubic metres, citing low water inflows into Kariba Dam during the 2014/15 rain season, resulting in intense load shedding throughout the country.
In January this year, it further cut down water usage to 20 billion cubic meters. The decision to cut the water usage was to ensure that water would be conserved so that generation of electricity could continue to the next rain season.
This came against the backdrop of a severe water crisis in the Zambezi basin leading to low inflows into Lake Kariba, the world’s largest man-made reservoir.
The move worsened the power supply situation in the country at a time Zimbabwe was battling machine breakdown at its four thermal power stations.
Zimbabwe has been experiencing crippling power shortages, with national demand at peak periods estimated at 1 600MW, against available generation of about 1 000MW.
Hwange Thermal power station is the biggest electricity plant in Zimbabwe.
Hwange Thermal Power Station, the biggest electricity plant in Zimbabwe, is producing 353MW, according to this week’s official figures, against installed capacity of 920MW.
The Harare Power Station is producing 26 while Bulawayo Power Station is generating 16MW.
Munyati Power Station is producing 17MW.
The country has been importing from regional power utilities to cover supply shortfalls, but this has also not been enough to meet demand.
Imports are currently coming from Mozambique’s Hydro Cahora Bassa, which has been supplying a paltry 50MW, and from Eskom of South Africa.
The South African power utility is supplying about 350MW.
Kariba South Power Station has been producing relatively cheap and reliable electricity for the country at an average cost of US$0,02 per kilowatt hour (kW/h) while electricity generated from four thermal power stations at Hwange, Harare, Munyati and Bulawayo is at an average cost of between US$0,08 and US$0,16 per kW/h.
Power imports are coming into the country at a cost of about US$0,13 per kWh.
Electricity supply is expected to be one of the key drivers of government’s economic revival strategy under the Zimbabwe Agenda for Sustainable Socio-Economic Transformation (Zim-Asset).
Zim-Asset envisages increased access to electricity by domestic consumers, both within urban set ups and rural communities.
A poor rainfall season implies reduced river water in-flows into Lake Kariba which in turn reduces water available for power generation.
A subdued electricity situation has serious repercussions on the recovery of the productive sectors of the economy such as manufacturing, agriculture, mining and tourism, which government wants to drive the country’s economic recovery.
Unstable power supplies cause companies to incur heavy losses as some processes are interrupted thereby affecting the quality of products.
Some processes are also delayed or aborted resulting in failure to meet deadlines and targets for many companies.
Government, through ZPC, is however working to close the electricity deficit in the country through the expansion of Kariba South Hydro Power Station to add 300MW to the national grid.
Work to expand Kariba by Sino Hydro is currently underway.
The country is also pursuing the Hwange Thermal Power Station expansion project which would see the country’s largest coal-fired power station, adding two more units to give a combined generation capacity of 600MW.
It is also pursuing the Batoka Gorge power project along the Zambezi River.
ZPC is also pursuing the establishment of solar power plants and has identified possible sites in Gwanda, Zvishavane, Munyati and Plumtree.
The Munyati and Zvishavane sites already belong to ZPC.
ZPC is also planning a mini-hydro power station along the Gairezi River in Manicaland.