As coal being extracted from underground coal mines, methane gas is released into the atmosphere directly through the ventilation systems. Such fugitive emissions of methane also contribute to climate change and methane is estimated to be 25 times as potent as CO2.
Coal mine methane emissions are mainly of two types:
- Drainage gas consists of >25 vol% CH4 in air
- Ventilation air methane (VAM) consists of <1 vol% CH4 in air
Technological options available to date for VAM mitigation are thermal flow reversal reactor, catalytic reversal flow reactor, concentrators and lean fuel gas turbines.
VAM mitigation is challenging due to:
- High temperature operation poses fire and explosion risk.
- The dust and moisture present in the VAM significantly affect the process and also deactivate the catalysts.
- Exceptional characteristics of VAM such as large volumetric flow, lower methane concentrations and fluctuations in both make it very difficult to use for power generation.
Therefore, as a step change solution, Dr. Kalpit Shah and his team at the University of Newcastle have devised an innovative process known as SDL (Stone Dust Looping), the development of which has been generously supported by the Australian Coal Association.
The SDL process works on the principle of catalytic oxidation followed by CO2 capture.
The SDL process development has positioned Australia as a world-leader in innovative, zero-emission VAM abatement technology.
Dr Kalpit Shah and Prof. Behdad Moghtaderi, Chemical Engineering, University of Newcastle, Australia.
Dr Shah’s current research projects and career interests include the fundamental and applied research in the area of advanced thermochemical conversion systems.
His self-patented technologies such as Chemical Looping Air Separation (CLAS) for oxygen production, Chemical Looping Oxy Combustor (CLOC) for coal combustion and Stone Dust Looping (SDL) process for Ventilation Air Methane (VAM) mitigation have gained significant interest from industry and global research community.
Professor Moghtaderi’s research expertise is in the general field of energy and the environment.
He has broad experience, knowledge and achievements in this field, particularly in application areas, such as renewable energy resources (e.g. biomass combustion / gasification, and geothermal power cycles), fire safety science, hydrogen powered micro-energy systems, and energy efficiency in buildings.
Potential features and benefits
- The novel process uses stone dust (limestone) as a raw material, which costs roughly $200/tonne.
- The operating temperature of SDL is also 40% lower than conventional processes of VAM mitigation.
- The process is highly tolerant to dust and moisture.
- The SDL process can operate, without auxiliary fuel, at methane concentrations as low as <0.1 to 0.05 vol%. No other technologies can provide self-sustainability at such low concentrations.
- SDL is the only Australian VAM abatement process, which provides a near zero emission mining option.
The process is at pilot scale demonstration phase.
Potential application and market opportunities
Globally, it is estimated that CO2 equivalent emissions resulting from coal mining is nearly 400 million tonnes per year and estimated to grow above 450 million tonnes by 2020 according to the US Environmental Protection Agency.
Of the total methane emissions from coal mines worldwide, 70-80% is mainly from VAM. Hence, mitigating VAM has become top most liability for coal mining industry in Australia and overseas. The worldwide market potential for VAM abatement technology is estimated to be > 10 billion US Dollars.
A PCT application was filed in July 2014.
Expressions of interest are sought for licensing partnerships with a view to commercialisation.