For the past 20 years, an energy project on the outskirts of Darwin has been quietly generating renewable electricity 24 hours a day.

It comes from a huge pile of the city's waste.

As organic matter disposed of at the Shoal Bay Waste Management Facility breaks down, it produces landfill biogas.

Renewable energy company LMS Energy uses that biogas to fuel a modified Caterpillar engine, producing about 10,000 megawatt hours of electricity annually.

"It powers about 1,200 homes on an annual basis. That's pure, renewable power," LMS Energy director Stuart Glenn said.

"It's also the equivalent of planting one million trees — reducing emissions by roughly 65,000 tonnes-equivalent of carbon dioxide."

Methane trapped and used

Over the lifetime of the operation the facility has abated enough carbon dioxide equivalent to removing 462,000 Australian cars from the road for a year, according to LMS Energy. 

While the electricity produced at Shoal Bay is a small contributor to the overall Darwin-Katherine electricity grid, utilising the biogas instead of letting it escape into the atmosphere is also beneficial for the environment.

"The waste, as it degrades, produces a biogas which is predominantly methane," Mr Glenn said.

"That methane is a very bad greenhouse gas, so the objective is to capture that so we can reduce the emissions that come from the landfill and also beneficiate that by generating electricity from that gas."

As Darwin produces more waste, the pipes and wells that capture the biogas need to be moved.

LMS Energy has installed over 200 gas wells since the facility started.

"It's a live process," Mr Glenn said.

"Not only do we have to keep drilling as new waste comes in, [but] as the waste settles it's not even. So we get breakage and kinking in pipes. So it's an ongoing process [to] remove the gas and pipe it to our power station.

"As Darwin continues to grow and as the landfill expands there is the ability to increase generation."

Encouraging a circular economy

Darwin City Council executive manager for environment and waste services Nick Fewster said revenue from the sale of electricity was re-invested back into the Shoal Bay facility.

"Waste management has a lot of different technologies and opportunities for the future," he said.

"We're looking ahead at how we can power onsite, using our renewable energy, different commercial operators that will help with the circular economy and [further] diverting waste from landfill."

LMS director Mr Glenn said many people did not understand how technical waste management was and the value it could provide to the community.

"People think about waste as a reasonably rudimentary process, but it's quite technical if you look at the sophistication and engineering of landfill design, followed by the well-field — how it's drilled, designed, and maximised to capture methane," he said.