The Bethlehem Hydro Project (BHP) in the Free State Province of South Africa was the first grid-connected independent hydropower plant in the country. Comprising two separate mini hydropower stations, the scheme was conceived to generate renewable electricity from the constant flow of water running into the Ash River as a result of the Lesotho Highlands Water Project (LHWP).
Since 2002, Aurecon Africa, now known as Zutari, has been partnering with Renewable Energy Holdings (REH), the developer of BHP, on small hydropower projects. In view of South Africa’s strict and rigorous environmental legislation, Zutari was appointed to assist with a comprehensive environmental impact assessment (EIA) scoping report. This involved an extensive public participation process (PPP) and the compilation of a detailed environmental management plan (EMP).
Overcoming hydraulic and geotechnical challenges
Zutari was then appointed to undertake the detailed design and project management duties for the two hydropower stations, one at Merino and the other at Sol Plaatje. A key design feature of the Merino site is an 8 m-high mass concrete weir diverting water to a canal. To achieve the required spillway length, Zutari had to overcome significant hydraulic and geotechnical challenges.
Changing the layout of the power station for the Sol Plaatje Dam increased efficiency and generation output. This was achieved in a cost-effective manner and improved the annual energy production for low additional capital costs. Deep excavations were undertaken to provide the required back pressure on the turbine blades and minimise the possibility of cavitation possibility under part load conditions. Zutari also designed an ingenious horseshoe type spillway to cater for possible floods within a restricted space.
A key design feature of the Merino site is an 8 m-high mass concrete weir diverting water to a canal. To achieve the required spillway length, Zutari had to overcome significant hydraulic and geotechnical challenges.
Achieving a number of firsts
The BHP delivered a number of firsts for local hydropower stations, including:
- Installation of Kaplan turbines at the power stations, as this was the first site to offer the low head and high flow characteristics required for Kaplans
- Issuing of a non-consumptive water use licence (WUL) for hydropower generation under the new water act. It was also the first hydropower development to be issued with a generation licence by the National Energy Regulator of South Africa (NERSA).
- Obtaining carbon credits under the Clean Development Mechanism (CDM) in South Africa
Combined, the hydropower plants produce 37 000 MWh of clean energy annually, resulting in a decrease of emissions by approximately 34 000 tonnes of carbon dioxide. Constructed to international standards, the BHP is considered a ground-breaking sustainable project.
Anton-Louis Oliver, the Managing Director of Zutari’s client, REH, received a 2017 Mosonyl Award for Excellence in Hydropower from the International Hydropower Association (IHA).
*The Aurecon Africa business has been officially renamed Zutari as at 21 July 2020. Zutari acquired Aurecon Middle East on 20 November 2020.