Works are now complete on upgrades to biogas capture covers on a key holding lagoon at Melbourne Water’s Western Treatment Plant (WTP) in Werribee, lagoon 25W, which will see the total renewable energy generation from the plant increased.
After 20 months of work, the newly installed cover will now produce up to 65,000m3 of biogas per day and up to 7MW of electricity.
Melbourne Water identified the need for the new cover for the 25W lagoon in 2015, as the existing covers were coming to the end of their service life. The new replacement cover is better designed to stand up to the harsh environmental conditions as well as providing operational efficiencies.
The gas collection cover measures 171 m x 450 m or 7.6 ha (19 ac). It features an eastern and western section connected by a dual arched central panel. Each section of the cover operates independently, allowing for maintenance and cleaning of various segments to take place while other segments can continue to capture biogas and manage odour.
WTP has been harnessing biogas for more than 25 years. Lagoon covers collect methane-rich biogas from primary treatment lagoons for renewable energy generation and to manage odour.
Collecting the biogas for conversion to green energy is a huge benefit for the environment as it both eliminates the emission of methane, a damaging greenhouse gas, and reduces the plant’s demand for electricity.
Manager, Western Treatment Plant, Martin Bowles, said the investment in the new cover meant the plant could contribute even more power to Melbourne’s electricity grid.
“Prior to the new cover being installed, existing biogas capture efforts were already producing 95 per cent of the power requirements of the plant,” Mr Bowles said.
“This upgrade means the plant is regularly producing more power than it consumes, and we are able to supply power back to the local grid.”
The first biogas covers were installed at the plant in the early 1990s in order to reduce odour levels. The covers which were installed on the main sewage lagoon were very effective and also captured a large amount of biogas, and so the WTP biogas capture program was born.
Mr Bowles said the plant provided a unique source of energy for a growing Melbourne.
“Wastewater is a power source which is sustainable, renewable and reliable. We know there is even more we can do in terms of capturing this valuable energy at the plant and we are currently undertaking design works to maximise our biogas utilisation.”
WTP is a world leader in technical and environmental innovation. The site treats half of Melbourne’s population’s wastewater and produces around 40 billion litres of recycled water every year. It is also one of Australia’s most important wetlands for waterbirds, and is listed under the international Ramsar Convention.