University Of Newcastle: Methane Reduction: Chemical Looping
There are a number of commercially available technologies for the reduction of ventilation air methane (VAM) from underground coal mines.
However, their deployment at an operating mine would introduce safety hazards that cannot be mitigated by using existing mine safety protocols. They also require very large equipment, can be inflexible to operate and many mines do not have enough space.
Despite these limitations – and because they are the only abatement technologies currently available commercially – COAL21 has invested in two projects, the University of Newcastle Methane Reduction Safety Principles Project and the Centennial Coal Methane Reduction Demonstration Project. Both projects are addressing the known safety hazards associated with deploying commercially available VAM abatement technology at an operating underground coal mine.
One alternative approach being explored is the development of chemical looping VAM abatement technology which may offer the benefit of reduced safety hazards, smaller equipment size and/or greater operational flexibility. Chemical looping technology has been proven for other applications in other industries and this project is examining its potential benefits for VAM abatement.
The goal of this project is to demonstrate operability at five cubic metres per second (5 m3/s) scale. Commercial-scale deployment would require unit sizes of around 100 m3/s so further scale-up based on this project’s findings will be required.
The project aims to establish the operating limits of the technology, including:
- minimum methane concentration in VAM for self-sustaining operation (i.e. no need for a supplementary fuel source to maintain operating temperature)
- resilience to variations in VAM flow rate and methane concentration (expected to be much better than current commercial options)
- energy requirement to operate the unit (expected to be greater than current commercial options)
- scale-up rules for the technology, which will include an estimate of physical size for a commercial unit (expected to be smaller than commercial options, which are very large, and many mines have limited space).
Achievements and findings
While chemical looping is being studied elsewhere in Australia and overseas for other applications, this is the only project in the world examining its potential for VAM abatement.
The concept of chemical looping VAM abatement has been proven at small scale (1 m3/s) in a test unit constructed at the university.
A significant number of design changes were implemented during the test program to address some practical problems, after which the small test unit successfully consumed all methane fed to it in a stable manner and at lower operating temperatures than commercially available technologies. This outcome established its potential as an abatement option.
The test unit is being modified to operate at higher flow rates (5 m3/s) and over a larger range of methane concentrations. This will provide valuable information on operational flexibility and equipment size requirements.
The project commenced in July 2013 and successfully completed the small-scale (1 m3/s) test program in September 2016. Approval was then given to proceed with the larger-scale (5 m3/s) testing which will commence in December 2018 on completion of the necessary modifications to the test unit. The project is expected to be completed by March 2019.
The project team is working on completing the larger-scale testing following which the technology’s potential benefits will be assessed to determine whether further funding for a larger-scale demonstration is warranted.
Download the Project Snapshot