The Global Water Engineering (GWE) Cohral plant opened this month to extract green energy biogas from its waste water streams. This will in turn replace millions of dollars’ worth of natural gas currently consumed at the abattoir on Queensland’s Darling Downs.
The plant, the first GWE covered high-rate anaerobic lagoon in the world, will produce 183.3 gigajoules of energy a day when it reaches design capacity through the combustion of methane produced.
Saves CO2 equivalent to 2,700 cars
It also delivers high-quality waste water by extracting organic content, which it converts into methane to replace fossil fuels. The anaerobic digestion technology involved can remove over 90% of organic waste content.
“The green energy produced represents 40% of our current usage of natural gas and will produce direct ongoing savings year after year. The cost of construction is expected to be repaid inside five years,” said Oakey Beef Exports general manager Pat Gleeson.
Additional benefits include reduced greenhouse gas emissions, improved quality of wastewater and greatly reduced odour emissions from the plant.
“The effect of burning the methane will save the equivalent of 12,000 tonnes of CO2, equivalent to removing 2,700 cars from the road,” Gleeson said.
Project attracting global attention
Ian Macfarlane, the federal industry minister, said other countries would take note of the project.
“This is a good project whichever way you look at it, including as a community asset, as an industry initiative funded on its own merits without government subsidy, and as a scientific, energy and industry advance that produces green energy as it reduces emissions.
“This is one of the most modern—if not the most modern—meat works in Australia,” he said of the Oakey plant, which is already one of Australia’s largest beef export plants and is currently undergoing an expansion to increase production from 298,000 head a year to 560,000, with employment rising from 750 to as many as 1,400.
In addition to lowering the plant’s dependence on increasingly expensive supplies of natural gas, the GWE anaerobic digestion plant will simultaneously produce waste water far cleaner than typical waste lagoons.
Cohral technology uses concentrated anaerobic bacteria to digest 70-85% of the organic matter in Oakey’s waste water to produce effluent of higher quality than typical open lagoons.
Closed tank designs can achieve even higher digestion levels, with more than 90% efficiency achieved in service by GWE plants.
The biogas storage design selected for Oakey Beef—a 6,000cu-m capacity flexible PVC-coated polyester fibre flexible storage balloon—is engineered to be permanently gas-tight.