Landfill methane power generation at Woodlawn
From the December 2007 edition of Agriculture Today.
An open cut mine site under remediation as a methanerecovery landfill adjacent agricultural land is close to producing enough gas to start generating electricity to sell into the NSW power grid.
Waste dispatched by train by the parent company, Veolia Environmental Service, from its Sydney depot to the Woodlawn Bioreactor at Tarago, near Goulburn, has backfilled the mine site to a depth of 50 metres.
Peering into the pit from several hundred feet above, it is clear this is a drop in the bucket.
There is capacity for another 150 metres to fill the conical depth of the void, and a potential volume of 25 million cubic metres.
The life of the project could be more than 50 years; the goal is to generate maximum capacity of 200,000 megawatts each year.
The first generator has been built and up to 24 will be progressively constructed, one each six months, depending on how well gas production goes.
Each generator will produce just over one megawatt per hour.
"At peak production, Woodlawn expects to be able to generate enough power for 30 thousand homes," Woodlawn’s environmental manager, Justin Houghton, said.
A patchwork of underground pipes, built layer on layer as the pit fills, presently transports between 400 and 700 cubic metres of methane per hour to the surface before progressively being crushed under the increasing weight of waste.
"We are close to getting a constant volume of 700 cubic metres an hour, to be able to power the first generator," Mr Houghton said.
The power supply will be under contract to Energy Australia.
When the mine site closed in 1998 and Woodlawn took over, it accepted responsibility for remediation of the whole site and for ensuring potential pollutants associated with acid mine drainage, or leachate from the waste, do not flow off the site onto adjoining agricultural land.
Monitoring figures are regularly filed with the NSW Department of Primary Industries.
To further limit greenhouse emissions from the site operations, Woodlawn is assessing the feasibility of establishing on-site greenhouses and aquaculture ponds to use up the byproducts of generation - heat and carbon dioxide.
The company is researching whether it would be practical to offer the facilities as a teaching resource to regional educational institutions.
Contact Justin Houghton, Tarago, (02) 4844 6351.
