The challenge
Ventilation air methane is a source of fugitive emissions
Methane is the second most abundant greenhouse gas following carbon dioxide, and 28-times more potent than carbon dioxide per molecule in trapping heat in the atmosphere.
Consequently methane poses a unique challenge in the coal industry as risks associated with it are twofold. Not only is it a major safety hazard in underground workings but it is also a significant contributor to greenhouse gases (GHG) in the atmosphere.
Methane and other gases are often released from coal during mining processes and the large-scale ventilation systems used to provide a safe atmosphere for underground mine workers and equipment also flush out these gases from the exposed coal seam into the atmosphere.
Once in the atmosphere, this ventilation air methane (VAM), significantly adds to coal mining fugitive GHG emissions so the challenge is to reduce the GHG effects of VAM.
Our response
Novel fugitive methane mitigation technologies
We have developed four high TRL technologies (TRL 6-7) that aim to mitigate methane emissions by either utilising or enriching or destroying VAM.
The choice of technology implemented is dependent upon the methane concentration in the VAM process stream.
- VAMCAT: the generator - VAMCAT uses a catalytic combustion gas turbine system to produce electricity from VAM. It operates when there is ≥ 0.8% methane in the air.
- VAMCAP: the concentrator - VAMCAP collects, separates and concentrates methane from ventilated air using carbon composite monolithic adsorbents.
- VAMMIT: the destroyer - VAMMIT is a compact flow reversal reactor containing a newly structured thermal regenerative bed which destroys VAM containing ≥0.3% methane.
- CataVAM: the catalytic destroyer – CataVAM is the newest CSIRO technology. Based on high-performance robust catalysts and novel thermal catalytic regenerative bed design, it achieves self-sustaining destruction of low levels of VAM in the 0.2 to 0.4% range, and so is well suited to Australian VAM conditions.
The systems can be operated as independent units or be used together in different configurations, dependent on the needs of a coal mining operations and mine site conditions.
The modular configuration of the units makes them an economical solution for mine sites. They are easily transportable making it easier for mine operators to scale up their fugitive emissions mitigation efforts.
The results
Demonstrated VAM management
Our VAM technologies are world‑leading and possess significant advantages over others.
They have been developed and successfully proved at a large scale at a mine site using mine-generated ventilation air.
For example:
- VAMCAT technology has been fully demonstrated in real-world conditions. The VAMCAT prototype unit was operated with 0.8% actual VAM and produced 8 - 21kW electricity output
- VAMCAP technology has also been successfully demonstrated with actual VAM enriched from around 0.6% up to 36%
- VAMMIT technology has been successfully demonstrated with actual VA with 0.3 to 1% methane. It achieved greater than 96% methane oxidation efficiency, reducing methane in flue gas to below 0.02%
- CataVAM technology has been trialled and demonstrated at a mine with actual VAM with 0.15 to 0.5% methane, which achieved over 97% methane oxidation efficiency. CataVAM offers a new approach to the destruction of VAM. It can operate effectively in much lower methane concentrations, has a smaller footprint, allows for a higher VA throughput, requires less energy to operate, and has a lower operating temperature offering benefits in safety management.
With all necessary operating data, engineering and safety management experience, these units are ready for further scale up in Australian mines, with the potential to be used in overseas coal mines, such as in the US, China and India.