13 July 2012
National Greenhouse and Energy Reporting (NGER) higher order methods
Using higher order methods for open cut coal mine fugitive emissions enables you to create site specific estimations reflective of your coal seam.
Any reduction in reported emissions will have a significant financial implication under the carbon pricing mechanism (commenced on 1 July 2012 with an initial $23 per tonne of carbon price).
The National Greenhouse and Energy Reporting (NGER) Determination provides three possible Methods for estimating fugitive greenhouse gas emissions from open cut coal mines.
Method 1 estimation is based on a default emission factor as follows:
Open cut mines in NSW – 0.045 tCO2-e/t ROM;
Open cut mines in QLD – 0.017 tCO2-e/t ROM.
According to ACARP, these current factors are based on estimates of emissions from ten coal mines in Queensland and seven coal mines in the Hunter Valley.
The values obtained were averaged noting that the emissions estimates varied largely between mines.
Higher order methods
Methods 2 and 3 allow for facilities to estimate a site-specific emission factor based on sampling of the gas concentrations in the coal seam to be mined.
The method requires the creation of a gas assignment model based on borehole gas composition analysis and a geological model of the area mined. These models are then combined to form a fugitive emissions estimate.
Moving to a higher order methodology to estimate fugitive emissions from open cut coal mining could deliver significant reduction in carbon liability if the site specific emissions factor is lower than the default factor.
Mine A is an open cut mine in NSW. Gas desorption testing from a number of boreholes has resulted in average gas compositions of 19% for methane and 32% for carbon dioxide. The mine forecast is for 14 Mt ROM next year.
Energetics can help
The model provides a means for estimating fugitive emissions on a mine by mine basis.
review gas borehole sampling test results and apply these to a geological model of the mining area in order to provide an initial estimate of emissions based on the ACARP methodology.
provide an indication of the magnitude of the potential reduction in carbon permit liability if moving to a higher order method.
We have internal expertise in engineering in coal mining operations, as well as verification and audit of NGER reporting.