Researchers from UNSW have found a way to dramatically increase the amount of methane produced by naturally occurring microbes.
The industry co-funded research, published this week in Energy and Environmental Science, could help prolong the life of coal seam gas wells, reducing the need to drill new ones. It could also boost production of biogas collected from food waste.
The team discovered crystals which act as electron shuttles, delivering more energy to the methane-producing microorganisms. “They just start serving electrons up on a platter," says senior author of the study, UNSW Associate Professor Mike Manefield.
The crystals, made from a synthetic dye called neutral red, led to a substantial tenfold increase in methane production.
“When we added neutral red in the laboratory to a mixture of coal and naturally occurring groundwater microbes, in the absence of oxygen, we discovered it formed crystals that had never been seen before," says Manefield.
Extending the life of a gas well
Coal seam gas wells have a short lifespan, leading to a growing expansion of the well network which is expensive and damaging to the environment. “It’s scarring the landscape,” says Manefield. In 2013-14, coal seam gas accounted for 12% of total gas production in Australia.
The group’s field trials showed that the crystals could extend the life of the gas wells for at least two years, according to UNSW research fellow Dr Sabrina Beckmann.
“After which, they degrade and can be re-added to further extend the life of the well," Beckmann says. “Neutral red crystal could help recycle a lot of abandoned coal gas wells, instead of drilling new ones."
Neutral red is traditionally used as a textile or histology dye, and can be produced cheaply. The researchers found these crystals could not contaminate the environment.
Dr Paul Jensen from University of Queensland, who was not involved in the research, agrees there is potential for the discovery to be applied to the coal seam gas industry.
“Coal seams are a tough environment for these microbes to grow,” he says. “The neutral red crystals will help them out.” However, Jensen stresses that at this point it’s difficult to determine exactly how long the well life might be extended.
“It’s just mad not to take the gas off those seams first,” says Manefield. “For me, taking gas from an existing coal seam is much more elegant than digging a [new] coal seam.”
Towards clean biogas production
The UNSW team is currently looking to run further trials – to gain a clearer understanding of how to harvest biogas.
Biogas is a renewable energy source produced by the natural breakdown of organic matter - such as food waste - by microorganisms. The gas can be used as fuel, electricity and heat. Biogas currently makes up 4.7% of renewable energy consumed in Australia.
“Biogas production by methane producing microbes has a large role to play in meeting the energy security of the human race into the future, whilst reducing greenhouse gas emissions compared to coal and petroleum combustion,” says Beckmann.
“As global energy needs rise, the need to make the most of the resources that we have is increasingly important.”