The launch of Bloemwater Conduit Hydropower Plant in Bloemfontein
On Tuesday, 31 March 2015 Minister of Water and Sanitation, Nomvula Mokonyane unveiled the Bloemwater’s conduit hydropower facility at Brandkop Reservoir and celebrated the major scientific and engineering achievement made by the team of researchers.
South Africa is currently facing an energy crisis which places additional importance on harvesting all available feasible renewable energies. While the country is not particularly well endowed with hydropower conditions, large quantities of raw and potable water are conveyed daily under either pressurised or gravity conditions over large distances and elevations.
The University of Pretoria supported by the Water Research Commission and collaborating organisations such as the City of Tshwane Metropolitan Municipality, Bloem Water and the eThekwini Municipality, were engaged in a research project to investigate and demonstrate the potential of extracting the available energy from existing and newly installed water supply and distribution systems.
The aim of the project was to enable the owners and administrators of bulk water supply and distribution systems to install small-scale hydropower systems to generate hydroelectricity for on-site use and, in some cases, to supply energy to isolated electricity demand clusters or even to the national electricity grid, depending on the location, type and size of installation. It taps into an unutilised source of hydropower by using excess energy in pressurised conduits to produce clean and renewable hydroelectric power.
This type of energy generation, referred to as conduit hydropower, is different to conventional hydropower generation where large dams are used to store river water in a reservoir. Its simplicity is what makes this solution so elegant: harnessing energy that is already present within the existing infrastructure and that would usually be lost through the use of a pressure valve.
This initial scoping investigation by the WRC and the University of Pretoria highlighted the potential of hydropower generation at the inlets to storage reservoirs. In South Africa there are 284 municipalities and several water supply utilities and mines, all owning and operating gravity water supply distribution systems which could be considered for small, micro and pico scale hydropower installations.
The application to install hydroelectric turbines in a water distribution system is fairly new in South Africa, and thus three pilot plants were constructed showcasing several of the intricacies in the development process and to demonstrate the technologies. These sites included City of Tshwane, Ethekwini Municipality and the Brandkop Reservoir in Bloemfontein. The research project indicated that it is feasible and technically possible to generate energy from distribution systems.
The WRC and Bloem Water then entered into a partnership to install the first full-scale demonstration unit for conduit hydropower in South Africa. This technology has proven to be a huge success in converting to a sustainable energy source as the main supply of energy for operating the Bloem Water head office in Pellisier. It supplies 96 kW/h of energy from a pressurised conduit, to power up its operational facilities, with a full capacity of 360 kW.
The Caledon–Bloemfontein potable water supply system supplies the majority of the water demand in Bloemfontein. The water is supplied to the Brandkop Reservoir, which is where the Bloem Water head office is located. Excess energy is dissipated through pressure control valves before being discharged into the reservoir. The benefit of this hydropower-generating application is that minimal civil works are required. There are virtually no negative environmental or social effects requiring mitigation and the anticipated lead times are short.
Approximately 30% of the water supplied via the Caledon–Bloemfontein pipeline is diverted through the turbine. Sufficient renewable energy is generated to supply the peak demand of Bloem Water's head office as well as meeting the electricity requirements of the reservoir terrain. Annually ±800 MWh could be generated with this micro-hydropower installation.
This demonstration project will provide huge savings for Bloem Water, as well as a quick return on investment. Bloem Water may soon become a serious player in energy as well. A good international example of such could be drawn from the German company Zweckverband Landeswasserversorgung that delivers water to three million customers in Baden-Wurttemberg and Bavaria. Since the early 1970s they have been using power generated continuously from energy recovery.
Hydropower schemes have very long lifetimes and high efficiency levels with low operating and maintenance costs. Hydroelectric energy technology is a proven technology that offers high efficiencies as well as reliable and flexible operation.
Contact: Executive Manager for Water Use and Waste Management, Mr Jay Bhagwan