Sydney has commissioned the first sewage-powered hydro-electric plant in Australia, in an effort to curb carbon emissions.

The plant generates power by dropping treated wastewater down a 60-metre shaft. The power produced will be used to meet about 40% of the ETPs captive power requirement.

The plant is expected to reduce 12,000 tonnes of CO2 a year and is part of a $50 million upgrade to the North Head sewage treatment plant.