UP researcher leads the way to green hydropower for remote communities

Posted on October 04, 2021

A University of Pretoria academic has helped to design and build an innovative small-scale hydropower plant to generate 50kW of electricity for the remote rural village of Kwa-Madiba in the Mhlontlo Local Municipality, north-east of Mthatha in the Eastern Cape.

The new plant was handed over on 4 October 2021 at an official ceremony that was attended by senior officials of the Ministry of Higher Education, Science and Innovation, along with representatives of UP, the Water Research Commission (WRC), Mhlontlo Local Municipality and the Kwa-Madiba community.

“The Kwa-Madiba scheme borrows a small proportion of water flowing over the Thina River Falls by diverting it into a steep and narrow tunnel,” said Marco van Dijk, a lecturer in UP’s Department of Civil Engineering in the Faculty of Engineering, Built Environment and Information Technology, and principal researcher for several WRC projects. “This precious resource is then returned to the main river after its power has been harnessed to spin a turbine. This renewable energy is green because it does not generate fossil fuel carbon emissions that drive global climate change.”

Thina Falls, the site of a new small-scale hydropower plant in the Eastern Cape. The turbine plant is housed in the grey shipping container (centre).

At Kwa-Madiba, a 450mm diameter tunnel was drilled through the surrounding rock close to the Thina Falls to provide a penstock (a steeply sloped water passage that is used to divert water to spin the turbine). After passing through the spinning blades of the turbine, the water is then returned unpolluted to the main river. “Environmentally, the project will have minimal to no impact on the river environment due to the fact that only small amounts of river water will be rerouted through the turbine (then returned to the river almost instantly),” said Van Dijk, who received the WRC Knowledge Tree Award for Empowering Communities on 23 September 2021 for his role in steering the project to finality.

Such run-of-river schemes are also unlike large-scale hydro-electric dams that can inundate large areas of fertile land, disrupt fish migration and create other environmental disturbance. The Kwa-Madiba project, which has involved UP, the WRC and the national Department of Science and Innovation, also created very little visual impact on the scenic value of the Thina Falls, because much of the piping infrastructure is underground, while the turbine is housed in a small, 6m-long shipping container.

Importantly, Van Dijk said, the project team was able to participate in the public consultation process of the General Authorisation (GA) scheme in terms of the National Water Act (1998). This means that the revised GA system now allows for the construction of small-scale run-of-river hydropower projects without the need for a full-scale Water Use Licence process – provided that these schemes do not exceed 300kW and adhere to specific requirements. This is important, as the Water Use Licence process can be lengthy and costly, and act as a disincentive to the roll-out of similar cost-effective hydro projects.

An aerial view of the small-scale hydropower scheme at Thina Falls, showing the intake works at the top and the penstock leading to the turbine room at the bottom of the falls. The electricity is then fed to the Kwa-Madiba community, about 1km from the falls.

“South Africa is a dry country compared to the rest of the world, but there is no reason why the country’s water resources cannot be tapped to deliver green electricity to many isolated rural communities,” Van Dijk explained.

While the government is committed to providing universal access to electricity, the reality is that many isolated communities will not be connected to the national grid for the foreseeable future due to the high cost of transmission and distribution infrastructure to the more remote parts of South Africa.

However, Van Dijk said, there are several areas in the comparatively water-rich Eastern Cape, KwaZulu-Natal and Mpumalanga provinces where the Kwa-Madiba standalone scheme could be replicated or adapted with little difficulty, while other types of innovative small-scale hydropower schemes can be established in other provinces.

Van Dijk noted that South Africa has almost 4 500 registered dams and several weirs, transfer schemes and pipelines, many of which could be retrofitted to accommodate small-scale turbine systems nationwide – without reducing water yield or reliability of water supply. The Hydropower Research Group at UP is also compiling a national hydropower atlas for the country as part of another WRC-funded project.

The turbine plant is housed inside a retrofitted shipping container and generates enough electricity for about 50 rural homes.

This atlas, the first of its kind in South Africa, will help to identify areas where hydropower projects of different sizes can potentially be implemented. It will also provide information on the different technologies available. The researchers hope their efforts will provide policymakers with a way to address the current slow pace of small-scale hydropower development.

Researchers have indicated that there are several opportunities for retrofitted hydropower schemes across the country. Another advantage of retrofitted hydropower is that no new major infrastructure is required for energy generation. “What we are saying is: Let’s harness the water resources that we have responsibly, for the benefit of all,” Van Dijk said. “Small-scale hydropower projects like Kwa-Madiba have the potential to be integrated into a number of our river systems.”

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