As the head of MidCoast Council’s waste operations, Dave Rees was faced with a serious and sometimes smelly problem to solve.
Council’s landfills at Tuncurry and Taree accounted for 70 percent of its total greenhouse gas emissions.
The project: To address the issue, the council has introduced a new process that captures and destroys harmful gases created by organic waste at the landfills, with help from clean energy company LGI Limited.
The result: In the four months to June, the council reduced its carbon dioxide equivalent (CO2e) emissions by 5,150 tonnes and captured more than 540,200 m3 of biogas.
That’s the equivalent of taking 1,113 petrol cars off the road for a year.
As an added bonus, council has reported improved air quality and reduced odour at the tips.
“Your smelly, odorous stuff that's at the landfill … the gasses from that are destroyed and your odours at the site are significantly reduced,” said Rees.
So, what’s biogas?: Biogas is a type of fuel generated when organic materials such as food waste breaks down in environments with a lack of oxygen. It contains mostly methane and carbon dioxide (CO2).
“The anaerobic breakdown of organic matter in landfill produces methane, which is 28 times more harmful to the atmosphere than CO2,” Rees said.
How it works: To capture the biogas, gas wells and pipes are set up at the landfill, then the gas is sucked out through a flaring unit, burning at around 850 degrees celsius.
The flare destroys the harmful gasses and releases CO2 and water vapour.
At what cost to ratepayers?: LGI pays to build and operate the system, and makes money by claiming government-issued carbon credits - a percentage of which is paid to council.
The future: Currently the captured gas is being destroyed, but in future it may be used to produce electricity, too.
MidCoast Council is monitoring the flow of gas at the Taree site, with an eye to eventually building a facility that converts biogas into renewable electricity and thermal energy.
“Then the gas won't just be destroyed. It will actually be creating electricity as well,” Rees said.
Sustainable tech: Dr Prasad Kaparaju, a waste-to-energy expert at Griffith University, said harnessing biogas has a range of benefits.
Biogas can be converted to heat and electricity or refined to produce biomethane, which is an alternative to natural gas.
Circular economy: Kaparaju said significant potential exists for Aussie farmers as well.
On-farm biogas plants can convert organic waste such as livestock manure or crop residues into energy, allowing farmers to power and heat their properties, or send it to the electricity grid.
He said the leftover organic material from the process - containing nutrients such as nitrogen, phosphorus, and potassium - can then be used as an organic fertiliser.
“[A farmer] can produce the biogas and generate electricity. [They] can use it on the farm or supply it to the grid. Then the residual material can be spread on the farm as fertiliser … going for a closed loop.
“The organic waste is recycled back to the farm.”
Working example: One producer turning manure into electricity is Blantyre Farms in Young, in the South Western Slopes of NSW.
Liquid waste from the farm’s piggery flows into a covered pond, where biogas is captured and refined into methane.
The methane powers generators on the farm, excess energy is sold into the grid, and remaining waste is used as fertiliser.