Ventilation air methane is a source of fugitive emissions
Methane poses a unique challenge in the coal industry as risks associated with it are not only a safety hazard, but a significant contributor of greenhouse gas (GHG) into the atmosphere.
It 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.
Methane and other gases are released from coal during mining processes.
Underground coal mines use large-scale ventilation systems to move fresh air into the mine and flush out methane and other gases.
This dilutes methane released into the mine workings to enable safer working conditions.
However, the ventilation air methane (VAM) is ultimately vented into the atmosphere, significantly adding fugitive GHG emissions.
Fugitive methane mitigation technologies – capture, destroy, use
We developed a suite of three technologies that aim to mitigate methane emissions by either destroying or enriching the gas or capturing VAM.
The choice of technology implemented is dependent upon the methane concentration in the VAM process stream.
- VAMMIT the destroyer - VAMMIT is a methane mitigation unit with a compact flow reversal reactor with a newly-structured regenerative bed which destroy methane
- VAMCAP the concentrator - VAMCAP is a capture and enrichment unit which essentially collects and separates the methane from the ventilated air using carbon composites
- VAMCAT the generator - VAMCAT, uses a catalytic combustion gas turbine to create electricity from captured methane, deriving energy from what would otherwise be a waste product of mining.
The three VAM technologies are complementary.
Depending on the mine site conditions, a company may choose to use one technology or a combination of them
Both VAMMIT and VAMCAT work in environments with a low VAM threshold i.e. below 0.3%.
They can be operated as independent units or be used together in different configurations, dependent on the needs of the coal mining operations and mine site conditions.
At VAM levels below 0.3%, VAMCAP technology can enrich VAM from very low concentrations to a much higher concentration of 25 to 30%.
The enriched methane can be used to assist the operation of the VAMMIT and VAMCAT units.
And the waste heat from the VAMMIT and VAMCAT units can be then used by VAMCAP for stripping methane in a regeneration process.The modular confuguration 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.
Demonstarted 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.
- VAMMIT technology was successfully demonstrated with actual VA with 0.3-1% methane. It achieved greater than 96% methane oxidation efficiency, reducing methane in flue gas to below 0.02%
- VAMCAP technology has also been successfully demonstrated with actual VAM enriched from around 0.6% up to 36%
- 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
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 overseas coal mines, such as in the US and China.