Suntown Landfill Gas Project

Grid-connected, distributed generation, renewable
Location: Arundel, Gold Coast, QLD

The site

The project is a joint venture between the Gold Coast City Council and Energex energyimpact. Gold Coast Council's EPA licence to operate the waste facility requires the waste gas, which is approximately 50 per cent methane (CH 4 ), to be collected and burnt as fuel for electricity generation.

Gas created in the cells of the landfill site by the biological breakdown of deposited waste is environmentally damaging, with unpleasant odours, noxious elements and global warming potential. However, by utilising the high energy content of the gas, not only is electricity supplied to the National Electricity Market with emissions far below a conventional power station, but the local landfill gas emission problems are also greatly reduced.

Plant equipment and operation

The project involved the construction of a 1 MW generating plant driven by a Caterpillar reciprocating gas engine. A landfill gas extraction system was installed comprising a grid of vertical gas wells strategically situated across the completed landfill cells. A network of underground piping and manifolds interconnect the gas extraction wells and deliver the landfill gas to the power generation facility and flare station. The facility is expandable to 1.8 MW when additional waste cells become available to be tapped.

The landfill gas extraction and power generation facility incorporates a gas pumping station to create a vacuum on the landfill network and a flare station to burn off the gas unused in the generation of electricity. A gas conditioning plant reduces impurities to the landfill gas engine and a gas compressor provides gas at a suitable pressure to the gas engine. The landfill gas engine and generator plant are installed in a stainless steel canopy enclosure. A transformer and switching station increase voltage from the generator to high voltage, for connection to the local electricity supply grid for exporting the electricity generated.

Energy purchase and supply

The plant operates 24 hours a day, seven days a week,with an output of greater than 370 MWh/month on average. Power generated from the project is sold to Energex Retail under a 10-year arrangement. The plant is accredited to the MRET renewable energy scheme and Green Power. At full output capacity the project will save the equivalent of 78,000 tonnes of carbon dioxide per annum.