University of Sydney Researchers Working on Potential New Use For Landfill Gas

Atmospheric concentrations of methane are steadily climbing, currently two and half times higher than pre-industrial levels, according to the International Energy Agency. The world is pushing to reverse this trend in the face of climate change, and landfills especially have had to accelerate their efforts to stay on top of their methane emissions as the communities they serve grow. 

Some entrepreneurs are working to turn this waste industry challenge into opportunity, including researchers at the University of Sydney in Australia. They believe they may in time be able to deliver to landfill owners a novel application to capture more gas, while providing them with a new revenue stream. They developed a process that uses nonthermal plasma to extract methane that could be converted to a hydrocarbon-based fuel.

The team is eyeing hard-to-electrify sectors, particularly aviation, an industry in hot pursuit of cleaner alternatives to petroleum-based jet fuel.

The technology, powered by electricity from renewable energy, facilitates conversion of gas into products by inducing plasma discharge within gas bubbles. Because it requires no heat or pressure, the process consumes substantially less energy, according to Professor PJ Cullen from the University of Sydney’s School of Chemical and Biomolecular Engineering and Net Zero Initiative and a research lead.

While today’s larger landfills already have technology to capture, upgrade, and combust their gas emissions for electricity, Cullen touts the plasma technology as having added benefits.

“It generates a much more environmentally impactful and commercially valuable product than electricity made with the current process,” he says.

Albeit, landfill gas can be converted to renewable transportation fuel, which is more lucrative than power. But while it’s gaining traction, this application faces steep competition from electrification.

Still, sectors such as aviation and shipping cannot be driven by direct electricity. Rather they require a sustainable liquid fuel, Cullen says.

Enter plasma technology.  The specific system he and his colleagues are working on would pull methane from landfill gas wells. 

“The beauty is that this simple process captures almost the exact composition that we need for our [method],” he says.

Cullen envisions that the innovation born out of the University will be compatible with both large- and small-scale landfills.

“The technology should be easy to integrate. There are no catalysts, etc. in our process, making it highly robust,” he says.

His group is not the first to recognize the potential of plasma for gas conversion. Interest in the use of plasma for such applications is growing due to its ability to enable thermodynamically difficult reactions to occur at ambient temperatures and pressures.

Further, as a decentralized technology, plasma can be fairly easily integrated into multiple industries and is compatible with variable renewable energy types. The resulting product could be subsequently refined in established refineries.

Currently the research born out of Sydney University is lab based. However, through a startup called PlasmaLeap Technologies the scientists scaled a similar plasma-based approach for green ammonia with much of the technology transferable to the application they are working on now.

Their R&D evolves as Australia has joined the International Methane Mitigation Agreement. Established to curb methane emissions from liquified natural gas (LNG), commitments come from major LNG producers and consumers around the world.

Among other voluntary movements, over 150 countries have signed on to the Global Methane Pledge (GMP), launched at COP26. Participants collectively aim to reduce global methane emissions at least 30 percent from 2020 levels by 2030.  Scientists say reaching this target would put the world on track to limit global warming to 1.5 degrees Celsius compared to pre-industrial levels, in accordance with the Paris Agreement.

With an 800-megaton annual carbon footprint from air travel, aviation in particular is called on to make headway, driving the race joined by innovators like the Sydney University scientists and by others with their own technologies. Velocys is working on net-zero sustainable aviation fuel from municipal solid waste, commercial, and industrial waste.  LanzaJet has announced projects it says will lead to 300-plus million gallons of annual sustainable aviation fuel capacity.

Meanwhile the International Air Transport Association (IATA) has committed to achieving net zero carbon by 2050. Adopting sustainable aviation fuel could achieve 65 percent of the carbon reduction needed to hit that mark, IATA estimates.

But getting there will require generating substantial volumes of ultra clean product, capital, and policy support.

To kickstart the industry, the UK is mandating that a minimum of 10 percent jet fuel be sourced from sustainable feedstocks by 2030.  And in the U.S., the Inflation Reduction Act is stimulating activity by offering tax credits for sustainable aviation fuel.

Asia too has joined efforts to accelerate adoption of cleaner jet fuels.

Cullen is hopeful that the plasma work taking place at the University will open opportunity too—opportunity for both the waste industry and the world of flight to contribute to decarbonization. Aviation consumes a staggering 400 million tons of fuel a year.  So there is plenty of room for new innovations to support this hard-to-abate sector.