More load shedding beckons
By Phillimon Mhlanga
KARIBA – A sharp drop in water levels at Kariba Dam could result in the world’s biggest man-made lake being decommissioned for the first time since it was built in the late 1950s, in what could worsen the crippling power outages being endured by the country’s citizens.
Zimbabwe used to draw about 750 megawatts (MW) of electricity from Kariba South Hydroelectric Power Station, but this has been slashed to about 450MW, as of last week, owing to dwindling water levels at Kariba Dam — occassioned by a drought that ravaged the 2014/15 farming season.
This was after the Zambezi River Authority (ZRA), which manages the water reservoir on behalf of Zimbabwe and Zambia, reduced water allocation for power generation at Kariba from 45 billion cubic litres per annum to 33 billion cubic litres.
The current water level is the lowest since the dam was completed in 1958.
Power utility, ZESA Holdings, has responded by introducing a punishing load shedding schedule, which it has hardly adhered to. In some parts of the country, citizens are going for more than 24 hours, if not more, without electricity.
Now, the Financial Gazette can exclusively report that Zimbabwe is heading towards its darkest days in five decades as power generation at Kariba South falls to critical levels.
The lake is at the threshold of being decommissioned, which will remove Kariba South from the national grid.
What that would mean is that Zimbabwe would have to rely on Hwange, Munyati, Harare and Bulawayo power stations, which are producing a combined 600MW against a national demand of about 1600MW at peak periods.
According to this week’s power generation statistics, Hwange is producing an average of about 500MW; Munyati (24MW); Harare 30MW) and Bulawayo (17MW).
This would certainly strain the country’s frail economy further at a time the International Monetary Fund has revised downwards its growth forecast for Zimbabwe from 2,8 percent to 1,5 percent.
ZRA has cited poor rainfall and failure by the Zimbabwe Power Company (ZPC) — a unit of ZESA Holdings — and ZESCO, formerly known as Zambia Electricity Supply Corporation to uphold the prescribed limits for water usage in generating power as having contributed to the crisis.
In an attempt to stretch the water available for electricity generation until more water flows into the lake in the current rainy season, ZRA has further reduced the allocation of water for electricity generation at Kariba by more than 50 percentage points to 20 billion cubic meters from 33 billion cubic metres.
Even after taking this drastic measure, the authority does not think the worst is over yet.
“At this rate, the lake is likely to close the year at around 10 percent storage, which coupled with below normal rainfall forecast for 2015/16, demands for further reduction in generation capacity for Kariba in 2016,” said ZRA.
Should the projected poor rains come to pass and ZPC and ZESCO continue to disregard the authority’s directive, Kariba Dam could shrink by another 14 percent soon — a level which would be too low to generate electricity.
This would result in the total shut down of the power station, an outcome that can only drive the economy on the brink of collapse.
“At that point, they (ZPC and ZESCO) might just have to shut the generators off because they will be vibrating too much and no longer operating efficiently,” said a source at ZRA, who declined to be named.
A joint venture outfit owned by the governments of Zimbabwe and Zambia, the ZRA manages water in the Zambezi River basin, which is shared equally by the two countries.
ZPC and ZESCO operate power stations on the southern and northern banks of the dam respectively. Failure by ZPC and ZESCO to adhere to ZRA’s directive has resulted in steeped drawing down of the live storage to the present 24 percent level for October 2015, compared to 68 percent for the same period last year.
Compared to October last year, Kariba was 64 percent full while in September of the same year, it was 68 percent full. Of the total reservoir storage capacity, the dam has about 65 billion cubic metres live storage, a situation which leaves about 116 billion cubic metres as dead storage.
The dam has total water reservoir storage capacity of 181 billion cubic metres. Due to low water levels in the dam following poor rainfall, water allocation for power generation has since been reduced from 45 billion cubic litres per annum to 33 billion cubic litres.
The latest further slash means that ZPC would again be forced to revise downwards its generation capacity to well below 300MW, which translates to more load shedding across the country.
There is now growing fear that the water level may drop to a point where Kariba Dam may no longer be able to produce any electricity because that point would represent the bottom of the efficiency curve for the turbines.
Continuing generating electricity at the current levels would result in the lake falling below the minimum drawdown level of 475,5 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 would 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 country’s enduring power crisis has so far stalled economic growth and has forced the closure of many companies, the latest being Sable Chemicals, which was recently switched off the national grid.
Energy and Power Development Minister, Samuel Undenge said Sable was sacrificed as part of a short-term strategy to avail energy to other sectors. At least 500 employees were left jobless as a result of the move.
This week, ZRA said hydrological simulations done in June 2015 indicated that if current generation regime continued, the Kariba reservoir was going to hit the minimum operating level by the end of the last quarter of 2015 (0,73 metres above the minimum operating level of 475,50 metres).
This would lead to shut down of power generation activities at Kariba in the early months of 2016.
“Based on the Southern Africa Regional Climate Outlook Forum forecast and taking into account the prevailing hydrological situation, the water allocation for power generation at Kariba for the 2016 has been drastically reduced to the order of 20 billion cubic metres which is practically half of the 2015 allocation,” said ZRA.
“There was a consensus outlook for the 2015/2016 rainfall season over the Southern African Development Community region is likely to receive normal to below normal rainfall for the period October to December 2015 and the January to March 2016.
“This forecast is based on the fact that most models predicted that a strong El Nino will develop in the next several months and persist through the southern hemisphere summer 2015-16. This situation is likely to result in below-average river flows with direct impact on inflows into the Kariba reservoir, exacerbating further the energy generation capacity at the Kariba complex.”
Ben Rafemoyo, the deputy chairman for ZESA, said the situation was beyond the power utility’s control.
“Unfortunately, it’s only God, the Almighty who has the answer because as human beings, no matter how we plan, we don’t control rains. We pray hard that Kariba (Power Station), which has been our anchor power station because of its reliability, would not reach a point where we have zero generation.
“Unless some miracle happens, the dam normally fills up around April/May of each year. If the situation doesn’t improve, there is no other choice but to be shut down. But the danger is; if we reach the zero generation point, we then need three good rainy seasons to go back to normal supplies of water to generate electricity,” said Rafemoyo.
“At the moment Kariba should be used as a peaking station. Unfortunately, we have been running it continuously because Hwange and other small thermal stations were not reliable. Kariba should only operate during morning and evening peak periods so that we don’t stretch it.
“As you might be aware, Kariba is currently running four units and the other two are on statutory maintenance. So we should bank water and run it during peak periods (morning and evening only). There are a lot of options which include increasing imports. Right now I am on my way to a board meeting at ZESA where we are going to look at management proposals on how we can fill the gap to avert the looming disaster.”
Kariba Power Station, Zimbabwe’s biggest generator of electricity, has been producing relatively cheap and reliable electricity for the country but is no longer able to perform to its optimal due to reduced water availability.
About 60 percent of Zimbabwe’s electricity supplies have been from Kariba, which has been producing power at an average cost of US$0,02 cents per kilowatt hour (kw/h). The balance of about 40 percent of electricity has been generated from the four thermal power stations at Hwange, Harare, Munyati and Bulawayo at an average cost of between US$0,08 cents and US$0,16 cents per kilowatt hour.
Inefficiencies in the running of these thermal power stations, associated with ageing equipment make the domestic production of electricity relatively expensive compared to regional counterparts.
This has led to ZESA charging a relatively high final tariff of US$0,986 cents per kw/h to electricity consumers, which is a blend of hydro and thermal power stations costs.
In terms of distribution, industrial and commercial charges in Zimbabwe are relatively expensive at around US$0,0983 cents and US$0,1272 cents per kw/h compared to regional average of US$0,035 cents and US$0,076 cents per kw/h respectively.
Such a development has rendered Zimbabwe’s commercial and industrial activities less competitive. The small thermals were commissioned between 1946 and 1958 and have since reached the end of their design life, which is 25 years.
They are now in a deteriorating state with most of the plants requiring either life extension measures or complete replacement. Consequently, their generation capacity has seriously declined. The last unit of Hwange Power Station was commissioned in 1987, which translate to more than 25 years.
In order to mitigate the pending crisis, Cabinet has already approved the installation of emergency power plants powered by diesel generators as part of efforts to avert the worsening electricity situation.
Government is also exploring other renewable sources.
And to keep Zimbabwe out of the dark, ZESA is also looking further afield.
It is pursuing cross-border connections to tap available power from neighbouring countries, namely Mozambique and South Africa. Financial Gazette