A reply from the Minister of Public Enterprises, Mr Pravin Gordhan, indicates that the hydroelectric power stations of the Gariep and Vanderkloof Dams are making a valuable contribution to the country's power supply.
The volume may not be great, but neither is the cost, it is exceptionally low both from a financial and ecological perspective.
From 1 January 2021 to 20 November 2022, the two dams respectively generated 2 230 and 1 928 GWh of electricity.
These two dams are at the heart of the Orange River Project, which was launched in the 1960s. The Orange is the biggest river in South Africa, but its flow fluctuates drastically. The dams were built to limit flood damage, and to make the large quantities of water that used to flow away available for agricultural and urban purposes.
Without the Orange-Fish Tunnel, the impact of the current Eastern Cape drought would have been much more severe.
The generation of electricity is an added benefit. Turbines with the capacity to generate 340 and 240 MW, respectively, were installed in the Gariep and Vanderkloof Dams.
At present, it amounts to a mere 0,6% of one phase of load shedding and is, therefore, not an alternative for the country's large coal-fired power stations.
Its utilisation is further limited by the quantity of water required. While the average flow of the river is 365 cubic meters per second, the turbines require 800 cubic meters per second to function at full capacity.
What these hydro-powered turbines should, however, be compared to are the diesel-powered open cycle gas turbines that are used during peak hours of electricity consumption. In such a comparison, they are exceptionally cost effective.
In addition, coal and diesel emit about a ton of carbon for every megawatt-hour of electricity that is generated, while the 4 158 gigawatt-hours generated in this way leave a carbon footprint that is negligible.
So, these dams saved about 4 million tons of carbon during the period in question.
The FF Plus welcomes the fact that these hydropower stations are, unlike the rest in the Eskom grid, still maintained well enough to keep generating.
At this stage, while the dams have been overflowing for several weeks now, it ensures a reliable supply of power, even though it cannot eliminate load shedding.
The FF Plus would like to see a viability study conducted to look into the possibility of upgrading it to a pumped storage system.
This can be done by capturing the water that flows through the turbines during peak times just below the dam wall and pumping it back into the dam during the day using solar-powered pumps.
A viability study will indicate what such a project may cost and how long it will take to recover those costs.
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