Coal Seam Gas … The future or a threat? Photo: SMH – Glen Hunt
Did you know?
- It is estimated there will soon be 40,000 coal seam gas wells in Australia
- Conservative estimates suggest coal seam gas wells could draw 300 gigalitres of water from the ground each year?
- The industry could produce as much greenhouse gas as all the cars on the road in Australia?
- Modelling suggests the industry could produce 31 million tonnes of waste salt over the next 30 years?
From a major report by the abc in 2012 – http://www.abc.net.au/news/specials/coal-seam-gas-by-the-numbers/
How much water will the CSG industry use?
Australia’s Great Artesian Basin and its underground aquifers are a vital source of water; farmers and other bore users are given allocations for their use.
By this year, the Commonwealth will have spent nearly $150 million under the Great Artesian Basin Sustainability Initiative, capping bores and fixing pipes to conserve water.
The coal seam gas industry is entitled to remove massive amounts of water from groundwater systems.
The Queensland Government says that if CSG mining causes groundwater levels to drop below specified “trigger” points then companies must “make good” to affected water users. The trigger points are:
- a five-metre drop in bore-water levels for sandstone and fractured rock aquifers;
- a two-metre drop in bore-water levels for alluvial aquifers; and
- a 20-centimetre drop in the water table surrounding springs.
While the Queensland Government has set out the make-good arrangements, there is concern over how these will actually work in practice.
For instance, Rabobank wants more certainty on the question of how CSG will pay for future reparations because some of the impacts may not be evident for decades. The agri-bank wants CSG companies to take out insurance for this.
The Queensland Farmers Federation has sought more information on how the burden of proof will be established and on making good cumulative impacts.
Others such as the Basin Sustainability Alliance want to know how make-good will be enforced.
In addition to these provisions, the forthcoming Murray Basin Plan will set limits on groundwater extraction, including by the CSG industry. The states must enact these limits by 2019.
There is a fierce debate about the amount of water the coal seam gas industry will extract from underground, and what impact it may have on the sustainability of the Great Artesian Basin.
The industry suggests it will pull out somewhere between 126 gigalitres and 280 gigalitres a year, while the National Water Commission puts the figure above 300 gigalitres a year. Others, including the Water Group advising the Federal Government, suggest it is higher still.
What’s in all that water?
Water is pulled out of the ground as part of the coal seam gas mining process, because the gas – methane – is in the coal seam and held there at great pressure by water and other sediment layers.
To release the gas, the water needs to be pumped out of the coal seam and up to the surface in a process known as ‘dewatering’.
CSG water release
The Queensland Government has confirmed the toxicity of coal seam gas water to aquatic organisms is assessed against environmental standards after it is released into rivers and not prior to discharge.
The water that is pumped from the ground as part of the coal seam gas extraction process is very salty and contains a range of naturally present chemicals. It may also include heavy metals and radionuclides.
Once at the surface, the water is stored in huge ponds, treated with other chemicals and then put through desalination plants on the gas field.
This final process removes the salt, which is then stored in salt brine ponds for later disposal.
If the coal seam gas company treats the water to a standard where it can be used “beneficially” then that water is no longer considered “waste water”.
How much salt are we talking?
Estimating how much salt will be produced depends how much water is extracted.
If you take the mid-scale figure provided by the coal seam gas industry of approximately 200 gigalitres of water being extracted each year, and couple that with information about how salty coal seam gas water is, you arrive at 21 million tonnes of waste salt being produced over the next 30 years.
However, if you use the National Water Commission’s estimates of 300 gigalitres of water each year, this suggests 31 million tonnes of salt will be produced over the same timeframe.
The amount of waste salt being produced is important because the coal seam gas industry has not yet come up with a solution of what to do with it all.
Related Links –
- CSG waste products: Find out more about how much salt is generated, and what the industry plans to do with it all.
For more detailed information – http://www.abc.net.au/news/specials/coal-seam-gas-by-the-numbers/
What chemicals are involved?
Treatment of coal seam gas water is designed to remove unwanted contaminants.
– However, some chemicals remain in treated CSG water.
– They can include boron, silver, chlorine, copper, cadmium cyanide and zinc.
– At the concentrations present in the water being released, many of the chemicals would be toxic to aquatic organisms.
– However, environmental water quality standards apply to water in the overall environment after the release, rather than specifically to the water that is being released.
Related Links –
- CSG waste products: Find out more about what chemicals are produced as byproducts of coal seam gas
- Water release: The Queensland Government has confirmed the toxicity of coal seam gas water to aquatic organisms is assessed against environmental standards after it is released into rivers and not prior to discharge.
- For more detailed information re this article please visit –http://www.abc.net.au/news/specials/coal-seam-gas-by-the-numbers/