Building energy resilience in Western Cape wastewater treatment works

The Hartenbos wastewater treatment works (WWTW) in the Western Cape has implemented a hybrid microgrid consisting of solar PV and battery energy storage (BESS) to ensure operational continuity during loadshedding. The system, completed in September 2025 with a cost between R100 million and R112 million, allows the facility to island from the grid, reduce diesel reliance, and export surplus power. The project serves as a model for other municipalities to stabilize critical services and lower energy expenditures through embedded renewable energy.

• Wastewater treatment and water supply are significant energy consumers, representing approximately 17% of total municipal electricity use, making them high-impact targets for energy efficiency and renewable energy interventions to protect critical services from loadshedding.
• The Hartenbos WWTW microgrid integrates 4,536 solar modules with a 2.112 MVA installed capacity, approximately 4.5 MWh of battery storage, and a new 11 kV substation on a 3.5-hectare site.
• The project, completed in September 2025 and launched in November 2025, cost between R100 million and R112 million. It enables the facility to maintain operations during Stage 6 loadshedding via islanding, reduces diesel consumption, and allows for the export of surplus electricity to the municipal grid.
• Beyond solar and storage, further energy resilience and reduction opportunities for wastewater treatment works include the use of high-efficiency blowers and pumps, SCADA upgrades for process optimisation, variable-speed drives, biogas recovery with combined heat and power (CHP), and hydropower turbines on gravity pipelines.

APA

GreenCape (n.d.). Building energy resilience in Western Cape wastewater treatment works. https://greencape.co.za/wp-content/uploads/2026/03/GEER-Energy-resilience-at-WWTWs-case-study-DIGITAL.pdf

Chicago

GreenCape. Building energy resilience in Western Cape wastewater treatment works. n.d. https://greencape.co.za/wp-content/uploads/2026/03/GEER-Energy-resilience-at-WWTWs-case-study-DIGITAL.pdf.

Wikipedia

{{cite report |author=GreenCape |title=Building energy resilience in Western Cape wastewater treatment works |url=https://greencape.co.za/wp-content/uploads/2026/03/GEER-Energy-resilience-at-WWTWs-case-study-DIGITAL.pdf |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{greencapendbuilding, author = {{GreenCape}}, title = {{Building energy resilience in Western Cape wastewater treatment works}}, institution = {GreenCape}, url = {https://greencape.co.za/wp-content/uploads/2026/03/GEER-Energy-resilience-at-WWTWs-case-study-DIGITAL.pdf}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }