Biogas combined heat and power

The document outlines how anaerobic digestion (AD) in South African wastewater treatment works can be leveraged via combined heat and power (CHP) systems to produce electricity and heat, reducing municipal energy costs and greenhouse gas emissions. It provides technical benchmarks, such as an average electrical yield of 70kWh per tonne of sludge, and financial estimates, noting that retrofitting existing AD systems with CHP can have a payback period of 5-15 years and an IRR of 18-30%. The factsheet identifies that projects are generally financially feasible for WWTWs with an inflow capacity exceeding 15 million litres per day.

• Wastewater treatment works (WWTWs) represent a significant energy burden for South African municipalities, with water supply and wastewater treatment accounting for roughly 17% of total municipal energy consumption.
• While approximately 50 WWTWs in South Africa currently employ anaerobic digestion (AD), the resulting biogas is typically released or flared; however, there is potential to recover energy from 1,900 tonnes of wastewater sludge produced daily across the country.
• Biogas CHP systems can co-produce electricity and heat, with average performance metrics per tonne of digested wastewater sludge including a biogas yield of 35m3 (approx. 60% methane), an electrical energy yield of 70kWh, and a thermal energy yield of 75 kWh, achieving an overall conversion efficiency of 60-80%.
• The financial viability of biogas-CHP projects varies by installation type: retrofitting an existing anaerobic digester costs between R20-45 million per MW with a payback period of 5-15 years and an IRR of 18-30%, whereas a full anaerobic digester plus CHP installation costs approximately R40 million per MW with a longer payback period of about 15 years.
• For a biogas-CHP project to be considered financially feasible, the WWTW should ideally have an inflow capacity of more than 15 million litres per day (MLD).

APA

GreenCape (n.d.). Biogas combined heat and power. https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-7_Biogas-Combined-Heat-and-Power.pdf

Chicago

GreenCape. Biogas combined heat and power. n.d. https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-7_Biogas-Combined-Heat-and-Power.pdf.

Wikipedia

{{cite report |author=GreenCape |title=Biogas combined heat and power |url=https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-7_Biogas-Combined-Heat-and-Power.pdf |access-date=23 October 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{greencapendbiogas, author = {{GreenCape}}, title = {{Biogas combined heat and power}}, institution = {GreenCape}, url = {https://greencape.co.za/wp-content/uploads/2023/08/Factsheet-7_Biogas-Combined-Heat-and-Power.pdf}, urldate = {2026-10-23}, note = {Indexed by Climate Insights Directory} }