Sewerage plant creates own power

Plans to be energy self-sufficient by mid-2012

Melbourne Water will soon be using the sewage at its Western Treatment Plant in Werribee to produce nearly all of the plant’s power needs.

Power is generated at the Werribee plant from biogases captured in covered treatment lagoons. Biogas, mainly methane, is a by-product of sewage treatment.

Paul Pretto, General Manager of Asset Planning, said two more power generators would be installed so the treatment plant can produce about 95% of its annual electricity needs by mid-2010, demonstrating the excellent results that can be achieved by investing in renewable energy.

“The community has traditionally viewed sewage as a waste product, but that view is changing with improvements in technology meaning it can now be utilised more as recycled water and to create energy,” Dr Pretto said.

Renewable energy company AGL has worked closely with Melbourne Water since 1999 to build and operate the biogas-fired power plant at the Werribee site and both recently agreed to increase its generating capacity from 8 to 10 MW.

The agreement will increase on-site renewable electricity generation from 52 to almost 72 GWh/y, or about 95% of the treatment plant’s annual usage.

Melbourne Water already generates a third of its total energy needs as a by-product of the services it delivers, and since 2001, has reduced its greenhouse gas emissions by 50% through a mix of biogas and hydroelectricity.

This biogas-fired power plant is part of the organisation’s goal of achieving 100% renewable energy use and zero greenhouse gas emissions by 2018.

Melbourne Water uses a lot of electricity in moving water and sewage around the system, and believes it has an obligation to support the expansion of renewable energy in the face of climate change.

Since 2005, more than 200,000 MWh of renewable electricity have been generated at the Western Treatment Plant, preventing the emission of more than 260,000 tonnes of greenhouse gases.

The plant is expected to be energy self-sufficient by mid-2012, following installation of one further power generator. By then, the plant is likely to be producing more power than it needs and the excess electricity will be exported to other Melbourne Water sites.