Sundumbili Water Treatment Works energy feasibility study

A recent feasibility study at Sundumbili Water Treatment Works provides an economic and institutional analysis of energy management aimed at improving efficiencies, and the feasibility of renewable energy and the conceptual design of required renewable energy infrastructure.


A study into improving the use of electricity at the Sundumbili Water Treatment Works (WTW) in the iLembe District Municipality has identified several ways to operate the plant more efficiently.

The study included two main components: firstly, an economic and institutional analysis of energy management at the Sundumbili WTW aimed at improving efficiencies and, secondly, the feasibility of renewable energy and the conceptual design of the required renewable energy infrastructure.


Using power better

The Sundumbili WTW is a significant energy consumer and is rated at 1 400 kVA. It ensures that safe drinking water is pumped to reservoirs that service about 100 000 residents in 16 wards in the iLembe District Municipality. The design capacity of the WTW is 40 Ml/d, but it is currently operating at 18-23 Ml/d.

The study found that the plant was operating well, despite its ageing infrastructure. Plans to increase the number of areas it supplies makes it essential that maintenance and refurbishment is undertaken to ensure the plant functions optimally and continues to service the surrounding areas in the future.

Improving energy management and efficiency

The plant can improve its energy management and efficiency by pursuing several initiatives, including:

  • Upgrading the raw water and internal water works electrical equipment, such as the motors and control equipment.
  • Installing digital meters to monitor the plant’s electricity consumption and the efficiency of the motors.
  • Installing check metering at the points of supply to monitor and verify Eskom’s billing data.
  • Consolidating the two electricity tariffs that the plant is billed on to reduce costs: changing the tariff of the raw water pump from Nightsave Urban Small to Miniflex tariff could save up to R200 000 a year.
  • Monitoring the pump motors closely to ensure that there is enough time to procure new equipment before any major breakdowns.
  • Replacing damaged motors with induction motors which are more efficient and have a higher operating power.
  • Repairing or replacing the Power Factor Correction (PFC) at the pumps. If the PFC was operational, this would eliminate or reduce the reactive power drawn from the grid by the motors by raising the power factor closer to unity at the point of connection. This will bring the kVA demand closer to the kW demand, resulting in a lower kVA demand charge.
  • Developing an electrical layout diagram for the plant to identify where future equipment can be connected, like electricity meters and solar system connection points.

Once implemented, these measures will reduce operating costs, lower the plant’s carbon footprint, increase energy security and improve the delivery of potable water.


Solar shows the way

A municipal water treatment plant in KwaZulu-Natal could soon lead the way to a brighter future – by using solar power to augment the electricity supply.

A feasibility study into improving electricity efficiency and installing renewable energy at the Sundumbili WTW in the iLembe District Municipality has identified a solar energy option to operate the plant more efficiently.

The solar system will abstract, clean and treat raw water from the lower Tugela River to potable standards and pump it to consumers.

This initiative is particularly significant as loadshedding continues to hamper the delivery of essential municipal services that depend on electricity throughout South Africa.

Planning around loadshedding

At this stage, the feasibility study focused on the available land area, which limits the potential solar power that can be generated and does not enable the plant to be resilient against load shedding. Additional land will enable a larger solar plant, which in turn could allow for battery storage and prevent the plant from being affected by Eskom’s load shedding.

Securing an exemption from loadshedding is not possible. This means that the plant’s operators need to plan their work around the loadshedding schedules to minimise the interruption of water supplies for the surrounding communities.

A longer-term solution lies in installing a sufficiently sized renewable energy system to minimise the impact of loadshedding by using back-up power during outages.

Solar power is now a mature and well-understood technology that is readily available in South Africa. The technology is relatively simple to instal and minimal maintenance is required.

It is easy to integrate solar systems with the plant’s existing electrical system. Once installed, minimal interruptions of the daily operations can be expected, as solar systems require very little maintenance.

Solar power systems are modular and scalable, providing an opportunity to install a smaller system if funding is constrained and to gradually scale the system up as funding becomes available. The solar modules can operate for up to 25 years.


The feasibility study found that the plant has sufficient space to instal both rooftop and ground-mounted systems to deliver up to nine percent of the power required.

Four options were considered, each with various configurations of rooftop and ground-mounted panels, tracking systems that follow the sun and battery storage systems.

Each of the four configurations were analysed for their energy output, capital costs, operating costs, the number of years of payback and the equivalent reduction in the emission of carbon dioxide.

Feasible scenario

One scenario was chosen from the four as the most feasible solution to achieve a high energy yield at the lowest cost.

This scenario consists of grid energy supplemented by a ground-mounted tracking photo-voltaic (PV) system with bifacial modules and a roof-mounted PV system.

The system will cost about R5 million to install and about R60 000 a year to operate. It will lead to total savings of about R4.8 million in the first nine years, and over R12 million over 25 years.

The feasibility study focused on the existing available surface area at the plant – ground and rooftop – which could be considered as a phase one renewable energy solution. Should there be the opportunity to extend the surface area, such as to adjacent land, the renewable energy project could be extended and could be implemented as a phase two option.

The first phase involves acquiring funding, performing detailed site evaluations and starting the tender process. This will be followed by appointing contractors, construction and commissioning of the system. It has the potential to be implemented as a turnkey project and will need to include establishing the options and agreement for operation and maintenance of the solar infrastructure.

The second phase may include acquiring more land and funding before the procurement and commissioning of the additional renewable energy infrastructure. There may also be the opportunity for multiple beneficiation in the form of an agri-PV system which combines agricultural activities with solar power generation infrastructure.

The solar power option also offered an opportunity for the iLembe District Municipality to introduce and understand solar systems and if implemented, to train local technicians to operate and maintain solar systems. 

Creating economic opportunities

This has the potential to create economic opportunities for many technicians in local communities, as solar systems are expected to play an increasing role in providing electricity as loadshedding continues. This applies not only to institutions, but also to private and domestic consumers that are transitioning to solar power.

The Vuthela Programme’s feasibility study indicates that there is immense value in municipalities investigating the benefits of installing renewable energy systems: including cost savings, greater efficiency, better delivery of services, and a lower carbon footprint.

In addition, solar options provide the potential to open up and sustain a new sector within the economy of the iLembe District Municipality, while keeping pace with the global trend towards replacing fossil fuels with renewable energy.

Once the solar option is installed, the Sundumbili WTW will assist to create opportunities not only for the iLembe District Municipality and its family of local municipalities, but for many other municipalities, by showing the potential to reduce operating costs, improve services and stimulate economic growth, while also contributing to the transition to clean and renewable energy.

As well as ensuring efficient and effective service delivery within the municipal area, the study aimed to instil eco-friendly ‘green’ values and identify wider economic beneficiation opportunities in the district.

Improved and extended water services are regarded as great enablers for municipalities. Several spin-offs can be created through innovative solutions like water reclamation and energy generation.