Unconventional Gas

May 3 016Coal seam gas is an unconventional gas as it has a completely different recovery process from natural gas, also called conventional gas. Coal seam gas extraction requires more wells and therefore infrastructure than natural gas. If the gas is extracted from coal seams below the Great Artesian Basin, drillers penetrate the impermeable strata underlying the Basin then drill into the coal seams below. When the gas no longer flows from the wells they are capped with steel piping and cement to stop the water in the Great Artesian Basin leaking into the coal seams below.

Before the gas will flow, water must be extracted from the coal seam. If the coal seam is above the Great Artesian Basin, nearby bores in shallower aquifers with good quality irrigation water will dry up. The water sucked out of an aquifer on one property, could be somebody else’s irrigation allocation on the other side of the river. Drilling can release toxic chemicals, found naturally in the coal seams, into the water. Fracking, used to increase the flow of the gas if it does not flow naturally, may also release chemicals. During the fracking process, chemicals, sand and water are blasted into the well to fracture the coal seam.

Gas and water are piped to large central processing plants where they are separated. The gas is then piped to market and large amounts of salty water, often containing toxic chemicals, are discarded. Initially this salty water was piped to huge evaporation ponds. Leakages prompted a regulation that these ponds had to be lined then, as the volume increased, the water was treated in massive reverse osmosis (RO) plants designed to remove the salts, chemicals, toxins and heavy metals, such as lead and uranium, but not all can be removed.

The treated water is called ‘beneficial water’ by the government and mining companies and ‘RO water’ by most other people. Owing to the volume, particularly at the beginning of a well’s life, the mining companies are desperate to get rid of it. ‘RO water’ is used by industry; supplements town water supplies and creeks; waters gravel roads for dust suppression; and irrigates stock feed crops and planted native hardwood forests. The remaining salty toxic sludge is stored in lined ponds. Some companies have ‘pilot projects’ to drill another well below the coal seam and reinject the sludge and or waste water there. Desperate to convince the public that the salt was not a problem, the industry once talked of using it as table salt. Reports of toxic spills soon dashed that idea. Other proposals were to dump it in the ocean, truck it to a contaminated waste facility or construct a huge lined tank, build a pyramid of waste, and cover it. Due to the large amount of toxic sludge and the high costs of disposal it remained in ponds, waiting for experimental projects to find a solution or for the next flood to wash it away. One of the major concerns of people opposed to coal seam gas is the regulation, disposal and monitoring of this salty water as it has the potential to contaminate aquifers.

Experiments with another unconventional gas were being carried out beneath prime agricultural land at Hopeland, near Chinchilla on the Darling Downs. Linc Energy started a demonstration facility in July 1999, the world’s first gas-to-liquid plant operating on underground coal gasification (UCG).  UCG is produced from coal, in situ underground. The coal is ignited by an injection of oxidants through a well. The burning coal produces gas which is syphoned out of another well and captured. Currently people in this area are not allowed to dig down more than two metres and a court case is pending.

Initially, mining companies, armed with industry funded research, convinced state and federal governments that natural gas was running out and that unconventional gas was a low carbon energy source, a transition between coal and renewables. This new industry would pay state royalties, and create jobs and business opportunities in rural areas where unemployment was high. It ticked all the boxes – low carbon emissions, money for the coffers, jobs and a boost to rural economies. Perfect!

A Department of Climate Change report on Australia’s Greenhouse Emissions Trends published in 2009 stated that “a number of potential LNG projects based on coal seam methane have not been included, because coal seam methane has an intrinsically low C02 content and so these projects, if built, will not have a material effect on Fugitive emissions.”

The science wasn’t questioned until the industry was underway. Initially the carbon footprint of coal seam gas was said to be seventy percent less than coal. This changed to fifty percent when it was revealed that the initial comparison was made with brown coal which is not mined or used in Queensland or New South Wales. Again this figure was disputed when studies showed if fugitive emissions from coal seam gas were taken into account from the beginning of the extraction process, its full life cycle emissions were nearly the same as that produced by black coal. Therefore by exporting coal seam gas instead of coal, a foreign country gets the benefits of reduced emissions while Australia’s emissions increase due to leakage in wells and pipes.