A wastewater site in South Australia has been generating more electricity than it requires. 

The production of biogas – a by-product of the wastewater treatment process – at SA Water’s Bolivar Wastewater Treatment Plant was used to generate 3,099 megawatt hours of renewable energy in July.

The figure is the highest monthly level recorded at the site, which produces an average of 2,800 megawatt hours per month. 

During its record month,  the site reached 112 per cent energy sufficiency, which followed 106 and 98 per cent self-sufficiency in the two months prior. The excess green energy produced is exported to the electricity grid, further reducing the utility’s operating expenses.

The Bolivar site features 14-metre-high anaerobic digesters to capture and heat solid waste from the sewage treatment process and naturally break down the organic matter, with the resulting gases used to power the site’s large engines for various stages of the treatment process.

SA Water’s General Manager of Operations Chris Young says the energy produced has reduced the plant’s exposure to market volatility and saved thousands of dollars in operating electricity expenses.

“Being one of South Australia’s largest electricity users, it’s important we can continue to harness ways of making our operations as efficient and sustainable as possible,” Mr Young said.

“With recent volatility in Australia’s electricity spot market underpinning a significant increase in costs for both households and organisations like ours, we looked at ways to maximise the production and use of biogas to power our Bolivar site, particularly in times when prices spiked.

“While previously achieving an average of 85 per cent self-sufficiency at Bolivar, this has increased significantly over the past 12 months to reach a new average of 95 per cent.

“When you consider our Bolivar plant treats the majority of wastewater for metropolitan Adelaide, being able to achieve self-sufficiency is a significant achievement.

“The flow-on benefits of renewable energy sources like biogas also reduce our carbon footprint, and this will only grow further with thousands of solar photovoltaic panels and on-site battery storage set to be energised at Bolivar over the coming months.”