Coal Seam Gas - CSG
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Methane
Marsh gas, fart gas, sewage gas, landfill gas, biogas, coal seam gas, CSG, coal bed methane, CBM, CSM, LNG, CNG, or, natural gas. It is all methane. It is everywhere. Cows produce methane when they burp. Their droppings produce methane when it decomposes without air. Above is diagram of dog droppings being used to light a lamp in Cambridge MA USA. Most sewage treatment plants collect the methane from the anaerobic digestion process to run the plant. Measured over 25 years it is 70-130 times worse than CO2 as a greenhouse gas. If you bury organic wastes underground they will produce methane and start turning to coal. Most landfill rubbish tips have laid gas pipes to collect methane for power generation. |
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Coalification - Lignin to coalIf you look at lignin which makes up one third of wood, and compare it to coal, you can see that when lignin is compressed underground, the benzene rings have been squeezed together and the CH4 has been squeezed out. At first this is done biologically, then, as it is all buried deeper, heat and pressure take over the same task. The coal has small pores, and natural cracks called cleats, and methane clings to these and internal surfaces. Methane is held there by water pressure. It can be removed by reducing the pressure, or by being replaced by CO2 which is preferentially adsorbed. It can also be flushed out with nitrogen because this lowers the partial pressure. It is quite conceivable that flue gas cold be pumped through a coal bed to remove the CO2 while flushing out more methane. |
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Coal mine gasCoal mining has always been dangerous work due to the risk of methane explosion. Methane was first extracted from mines in the 90s as a safety measure, it was called methane drainage. Nowadays it is used to generate power. Before that it was released to the atmosphere and wasted and produced something like 10% of our greenhouse emissions. |
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FrackingTo extract the methane from un-minable coal seams, a bore hole is drilled and high pressure water and sand is pumped into the coal,. The water pressure widens the cleats, and the sand keeps them open so the methane can flow along the cleats. There are also various chemicals pumped in and these have caused harm to the water quality. There is great controversy on this. The companies claim they are safe, yet many wells have poisoned the underground water. Very few people know exactly what is in each batch of chemicals, and this has fuelled suspicion.
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ExtractionTo recover this gas, the underground water is removed, the methane will be released from the surfaces. This is the reason the water table must be lowered for methane extraction. Typical half-life of a CBM well has been 13 years. The standard method removes about half the methane. However it could do tens, hundreds, or even in some cases, thousands of years damage to the artesian basin. Methane can be removed by reducing the pressure. This can be achieved by removing the water, or flushing with nitrogen which reduces the partial pressure. The other way is to replace it with CO2 which is preferentially absorbed by the coal surface. It will not be long before someone builds a gas fired power station on a CSG well and pumps the flue gas back into the coal bed. This would carry out the capture and storage all in one step, and be quite cheap. Watch this space Ref... Page 15 |
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How much coal seam gas?Australia has an estimated 4,800 million tonnes of CSG. (235 trillion cu ft) |
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Chemicals used in fracking - fraccingIt is difficult to get the facts on this topic. The miners say there is nothing harmful, and the activists are seeing cancer in every chemical. The best lists seem to those published by governments who require the chemicals to be known.Methane info Also, the effects of various chemicals: http://art-metal.ca/hazardous-substances-overview/ |
Working with hazardous chemicals: http://www.safeworkaustralia.gov.au/sites/swa/whs-information/hazardous-chemicals/pages/hazardous-chemicals-other-substances Working with substances hazardous to health |
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Using flue gas to flush out methane and capture CO2Enhanced Coal Bed Methane (ECBM) and CO2 This excellent CSIRO report gives a very clear picture of methane from coal (Coal seam methane CSM). It looks at how flue gas which is a mixture of CO2 and nitrogen can be used to flush out more methane. The coal seam will be able to absorb 2 molecules of CO2 for every one molecule of CH4 (methane) flushed out. The total CO2 storage capacity in unmineable coal seams: in NSW is 4.1 billion tonnes, and in Qld is 1.7 billion tonnes. A similar report has been produced in USA: |
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Greenhouse emissions impactGas is no better than coal if the gas must be converted into and back from a liquid before it can be burnt. This happens with CSG shipped overseas. But burning domestic gas instead of coal avoids the liquefaction step, and consequently produces less greenhouse gas emissions overall. Industry claims a 70 per cent reduction in greenhouse gas emissions from burning CSG instead of black coal. With no leakage this would be the case. However there is leakage. A recent NSW Parliamentary Inquiry concluded that CSG emissions are, at worst, likely to equal those from coal. Environmental impact of CSG - report Summary from this report:
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Does gas produce less warming?Most researchers who have looked into the gas industry claims of methane being less damaging have found there is no advantage because of methane's greater greenhouse warming potential. |
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Grass roots organisations:Coal seam gas and regulation - what you should know about the law |
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According to Geosciences Australia, as at December 2008 the proven and probable (2P) reserves of coal seam gas (CSG, or coal bed methane as it is known elsewhere in the world) in Australia were 16,179 Petajoules, an 116% increase over the 2007 reserves. Coal and coal seam gas in NSW
If you want to see a map of coal in NSW then click on this map produced by the Nature Conservation Council of NSW - NCC
Coal Seam Gas in AustraliaThe ABC has produced this interactive map of known CSG sites in 2011. Click on this map to take you to the ABC website, then scroll down to their map and click on it. |
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CSG future production
We are heading for a massive increase in CSG wells.
The number of CSG wells will probably peak at 40,000 in the next 10 years.
5 Major Global players are planning to invest $30-60 billion. $30,000 per minute in Queensland alone.
Qld govt report on future of CSG
The discovery of huge reserves of coal seam and shale gas has relieved the world from the worry of peak oil. However it has postponed the urgency to develop green energy.
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The Great Artesian Basin
Many are worried the Great Artesian Basin will be polluted by mining in the recharge areas,where the rainwater sinks into the ground. Source: CSIRO |