Walter Nyamukondiwa Kariba Bureau
Construction of the 2 400MW Batoka Gorge dam and power station is picking up momentum with the Zambezi River Authority now submitting the necessary Environmental and Social Impact Assessment (ESIA) for review.
This is part of preparatory works that will pave way for the construction of the 181-metre tall gravity arc dam, about 54km downstream of the Victoria Falls, and the building of the pair of 1 200MW power stations.
Seen as a key project to meet growing needs for power in Zimbabwe and Zambia and boost the hydro component in the Southern African Power Pool, Batoka Dam, first mooted in 1972 as a potential site, is closer to being realised.
Batoka only really moved into the limelight in the late 1980s when environmental considerations killed the preferred technical solution of Mutapa Gorge for the second dam on the middle Zambezi.
Mutapa would have seen widespread inundation of high-value flood plains, including the Mana Pools, while Batoka with its long but narrow lake was considered to have a far lower adverse environmental effect, although it would present greater operational challenges.
Now the environmental effects have to be far more precisely described and calculated and the social aspects, principally the movement of communities, have to be shown along with the required steps to minimise adverse results and ensure that those moved are compensated and able to have long-term alternative livelihoods. There will be need to avoid the colonial era social mess when Kariba dam filled.
An environmental and social impact assessment has been done in communities around the proposed dam catchment, plus the impact of staff housing, roads and other key infrastructure that must be set up.
The Environmental Management Agency in Zimbabwe recently confirmed submission of the statutory document.
“The Environmental Management Agency received the Environmental and Social Impact Assessment (ESIA) for the proposed Batoka 2 400MW Hydropower Project in terms of Section 100 of the Environmental Management Act.
“Hydropower projects are regarded a prescribed projects which require an ESIA in terms of Section 97 of the Environmental Management Act. Once satisfied, EMA will issue an ESIA certificate, paving way for commencement of works.”
Zambia also has laws and the Zambezi River Authority, as the ultimate owner of the dam and the manager of the water supply, has to be able to satisfy legal requirements in both countries, as well as follow the procurement and tender rules in each country, especially for those aspects which are not common, like the access roads on each side of the river.
Already the Zambezi River Authority has invited bids for the maintenance of a 14,5km access road for the proposed Batoka Dam site on the South Bank, in Zimbabwe.
ZRA invited bids from eligible Zimbabwean registered bidders to undertake spot gravelling, general road maintenance, and construction and maintenance of drainage systems. Bids will close and be opened on October 19, 2022.
The Zambezi River and its tributaries have a total hydropower generation potential of 20 000MW, with slightly over 2 000MW being produced on the North and South banks as it runs between Zambia and Zimbabwe, representing about 20 percent of potential.
Zimbabwe’s industrialisation drive, particularly in mining and massive residential development, has seen the power deficit ballooning in recent years with a lot more demand on the horizon, so Zimbabwe needs more generation capacity for what is already there, plus more to cope with economic growth.
Several mines have been opened or re-opened, with more coming on stream including the Manhize Iron and Steel Plant, and several more gold and lithium mines across the country with a huge appetite for electricity.
Batoka will be a needed addition to the mix, and being hydro, is a green carbon-free station. The operational challenges arising from the Zambezi include a wide margin between peak and low water flows, and that long narrow lake with low storage, making Batoka more of a run-of-river scheme rather than the huge storage of Lake Kariba allowing those power stations to be operated with stored water and so maintaining average output over a year.
While Batoka is planned with twin 1 200MW power stations, each bigger than the two expanded power stations at Kariba, that sort of output is not sustainable over a year, but only when the river is in flood.
Basically the ZRA and the generation utilities will have to operate Batoka and Kariba as a pair, allowing Batoka to run flat out while Kariba cuts back during the flood flows and Lake Kariba fills fast, and then as Batoka cuts back as the floods recede, Kariba starts using the extra storage to run its two oversized power stations closer to flat out than is possible now.
The upshot is that Zimbabwe and Zambia both benefit significantly with extra power, but the extra will be on average noticeably lower than the total 2 400MW installed at Batoka. This is why the preferred engineering solution was for Mutapa, which would have regular inflows from the largely standard Kariba daily outflows.