Mine Site Greenhouse Gas Mitigation » Mine Site Greenhouse Gas Mitigation
This study was conducted in two parts: A feasibility study of pipeline options, conducted by Gutteridge Haskins & Davey and an assessment of seam gas reserves, conducted by CSIRO Exploration & Mining. The first part reviews the alternative pipeline scenarios available for connecting Townsville to the existing pipeline infrastructure currently supplying gas to Gladstone (Duke State Gas Pipeline). The routes reviewed included the proposed PNG pipeline route, which runs slightly inland between Townsville and Gladstone, and two alternative routes to Townsville from either Rolleston or Moura.
The report concludes that the initial capital cost for building the required infrastructure is substantially lower if one of the alternative more westerly routes is chosen. Savings of up to AUD $39 Million may be achieved for the supply of interim gas to Townsville. These savings include the direct savings on the cost of the pipeline as well as the inherent savings available by minimising the cost of upgrade work required on the Duke State Gas Pipeline. The two more westerly routes also offer the advantage of allowing access to pipeline infrastructure for the developing coal mine gas, and coal seam methane basins along these routes. The communities within these regions may also benefit by having access to the gas infrastructure, which could enhance other industrial development, as well as providing employment opportunities both during and after construction.
If and when the PNG project is completed, then additional infrastructure would be required to allow the same delivery volumes of gas to Gladstone from PNG. Whilst the total cost of this infrastructure is marginally higher than the direct route, the Net Present Value of the overall expenditure would negate this additional cost.
The report also provides an estimate for the construction of a smaller pipeline to supply gas to Townsville, in the event that the PNG pipeline does not proceed. The substantial pre-investment in the construction of an oversize pipeline running from Gladstone to Townsville carries with it a degree of risk if the PNG pipeline does not proceed. The construction of the pipeline along the alternative routes reduces the initial expenditure of capital, and also provides improved utilisation of the pipeline, by allowing easy access to both mine drainage gas and commercial Coal Seam Methane (CSM) supply sources that are located along the length of these routes.
The second part assesses potential gas reserves. The supply of high concentration methane from Bowen Basin underground coal mines in the period to 2012 is predicted to be 4011 Mm3 (154.8 PJ) for the "business as usual" coal production case. Potential annual pipeline production will trend upwards through to 2012, due to increased coal production and mines working deeper, gassier seams. This anticipates raw coal production from all underground mines in the Bowen Basin will reach 60 million tonnes per year in 2012, which continues the recent historical growth rate of coal production.
A lower coal production case reflecting maintenance of production at approximately current levels of 40 million tonnes of raw coal per year from underground, will produce a high concentration methane supply to 2012 of 2290 Mm3 (88.4 PJ). The potential annual gas production in 2012 would be 257 Mm3 (9.9 PJ)
A higher coal production case based on raw coal production reaching 80 million tonnes of coal per year from underground by 2012 would produce a high concentration methane supply of 6055 Mm3 (233.5 PJ) by 2012. The potential annual gas production in 2012 would be 742 Mm3 (28.6 PJ).
These high concentration methane supplies come from 10 current and future gassy underground coal mines, which experience (or anticipate) coal gas inflow to underground workings that have to be managed by a gas drainage system. Forecast production of raw coal from these gassy mines in the Bowen Basin will increase from 24.2 million tonnes in 2000 to 37.6 million tonnes in 2012 for the business as usual case. Other underground coal mines with lower gas content in the coal will not have drainage systems, and cannot contribute to a pipeline supply.
Future advances in gas drainage and capture technology (coupled with improved practice) during the period to 2012 should allow high quality in-situ gas to be pre-drained at higher and more consistent qualities, at or near pipeline quality, akin to current commercial coal seam methane operations in Queensland.