Fugitive methane emissions from coal mines
Why methane emissions?
Methane is a potent greenhouse gas. Methane is commonly formed underground during a natural process where organic plant materials are converted into coal. The gas is stored within coal seams and surrounding rock strata and can be released due to natural processes or mining operations.
Fugitive emissions from coal mining account for 8.9% of NSW greenhouse gas emissions (Scope 1 emissions in 2018-19). Most of these emissions are from underground coal mines in the form of ventilation air methane (VAM). VAM is very challenging for the coal industry to mitigate or use as an energy source because the air volume is large, and the methane resource is dilute and variable in concentration.
Funding innovation to reduce methane emissions
As set out in the Strategic Statement on Coal Exploration and Mining in NSW, the NSW Government is working to reduce greenhouse gas emissions directly associated with coal mining in NSW.
The NSW Government is funding projects that encourage greater investment in, and uptake of, VAM abatement technologies to significantly reduce fugitive methane emissions from coal mining operations in NSW.
In April 2022 the Deputy Premier and Minister responsible for Resources Paul Toole announced funding to establish a full-scale VAM abatement project that will demonstrate the effectiveness of the innovative technology for industry.
Mr Toole said “The NSW mining industry is committed to reducing fugitive emissions from coal mining” and that “our scientific trials in partnership with the CSIRO are delivering promising findings about abatement technologies and expanding these trials at an operating mine with a full-scale facility will show how technology can help to support a stronger and safer coal mining industry.”
“Coal mining continues to play an important role in our regional communities and while we’re supporting the responsible development of coal resources, we’re also working toward a lower carbon future,” Mr Toole said.
“Today we’re putting our money where our mouth is to encourage innovation in the coal mining industry with technology that could have applications in coal mines around the world. I thank and congratulate South32 for its commitment to innovation and its partnership with the NSW Government as we strive for continuous improvement in the mining sector.”
A co-contribution of $4.5 million will be provided by South32 to establish the facility.
Project: Full-scale ventilation air methane abatement facility
The challenge:
Overcome challenges of commercial scale VAM abatement and encourage industry uptake of the technology.
The action:
Coal Innovation NSW funded the VAM abatement demonstration project at a NSW coal mine.
Grant amount:
$15 million.
The project:
South 32 will design and construct a full-scale next generation VAM mitigation thermal reactor (termed a VAMMIT unit) demonstrated with improved safety and commercial viability. Long term testing of the technology and safety system will be conducted with results summarised and presented to the NSW Government and mining industry.
CSIRO has previously successfully trialled smaller-scale VAM technology at the Appin coal mine in southern NSW. Project success at full commercial scale would encourage broader industry uptake of this technology and drive emissions reduction from the sector.
VAM thermal reactor technology works by oxidising almost all the methane (>99%) in a combustion chamber heated to approximately 1000º Celsius. At this temperature the methane is converted to water and carbon dioxide (CO2), which has a significantly lower Global Warming Potential (GWP) than methane. A key feature of the technology is its ability to be self-sustaining as it doesn’t need additional energy to maintain the temperature in the combustion chamber.
VAMMIT pilot plant at Mandalong (courtesy of CSIRO)
Project: Ventilation air methane catalytic mitigator
The challenge:
Investigate novel technologies to reduce the VAM emissions from coal mining operations.
The action:
Coal Innovation NSW funded the development and site trial of a novel pilot VAN catalytic mitigator.
Grant amount:
Up to $1.5 million (EOI Round 2018).
The project:
This project further develops a novel CSIRO technology that aims to reduce the greenhouse gas emissions from underground coal mining.
This project aims to reduce the operating temperature of the VAMMIT to much safer levels by incorporating two layers of catalysts inside the refractory bed of the existing VAMMIT unit at Appin mine. The project also aims to improve the performance and safety of this technology. The project is ongoing, and the unit has been commissioned and is being trialled with VAM to demonstrate its performance.
Project: Greenhouse Gas Abatement Facility Demonstration
The challenge:
Investigate new technologies to reduce the methane emissions that can escape from coal mining.
The action:
Coal Innovation NSW funded the trial of a Ventilation Air Methane Regenerative After Burner (VAM-RAB) technology.
Grant amount:
Up to $2.2 million (EOI Round 2009).
The project:
Centennial Mandalong Pty Ltd received funding to trial a new technology called a Ventilation Air Methane Regenerative After Burner (VAM-RAB).
This technology oxidises almost all the methane (>99%) in a combustion chamber heated to approximately 1000º Celsius. At this temperature the methane is converted to water and carbon dioxide (CO2), which has a significantly lower Global Warming Potential (GWP) than methane. A key feature of the technology is its ability to be self-sustaining as it doesn’t need additional energy to maintain the temperature in the combustion chamber.
A demonstration plant was constructed at Mandalong mine to test the technology. Initial heat-up trials in 2014 revealed issues with the plant requiring an extensive remedial works to recommission the plant. However, the heating trials remained unsuccessful, as the required temperatures were not reached.
In early 2019, the project ceased by agreement of all parties, with a commitment to work with the Commonwealth and industry to navigate a pathway to the commercial deployment of VAM abatement technologies. The project highlighted the safety issues involved in abating VAM. Subsequently, a separate, Commonwealth funded project was able to achieve a safe design installation of VAM abatement technologies at an active mine site.
VAMRAB pilot plant at Mandalong (courtesy of CINSW)