The Drakenstein Municipality in the Western Cape is now home to one of the country’s largest pump and turbine stations which will be used for more than water reticulation.The facility, which is able to generate 57 kW with three turbines, will be used for water reticulation to the nearby town of Paarl during dry periods, and as turbines to generate electricity for the city during the remainder of the year. The municipality was previously forced to fork out thousands to maintain the pump station which was dormant for most of the year because it was only used to pump water to its neighbours for just one month a year.
Generating electricity for the gridThe solution allows the municipality to run its pumps backwards against the pressure of water from its elevated Leliefontein reservoir and generate electricity for the region’s electrical grid. The power generated by the pump and turbine station is enough to power the entire region’s water infrastructure of treatment plants, pumphouses, offices and other infrastructure for an entire year.
“The water comes from the City of Cape Town Wemmershoek Dam and is gravity-fed to our city regions via our main reservoir. For one month of the year during the driest month the pumps need to be switched on to pump 400 litres per second upstream to Paarl where after the pumps would usually be switched off,” explains Hein Henning, the City’s engineer for water operations.“However, the higher elevation of the reservoir allows us to rotate the pumps backwards to act as small turbines for the rest of the year which is able to generate electricity at more than an 80% efficiency. Unlike turbines however, the pumps are standard stock items from the supplier, KSB Pumps and Valves and does not require specialised support and servicing. What’s more, the pumps are durable enough to allow us to design the infrastructure with a 40-year lifespan.”