Water from coal
Producing water from coal is a common practice.
The first water well was drilled into the Walloon coals in 1928, many decades before CSG technology was developed.
Currently 1,647 bores unrelated to the gas industry are producing 11.4 billion litres of water every year from Queensland’s Walloon coals  (the state’s main coal seam gas-producing geological formation).
About 42% of this water is used for agriculture, and 53% for stock and domestic purposes.
To produce natural gas from coal, the pressure must be reduced by pumping water from the coals.
In our dry country, this water is an important resource that cannot be wasted.
CSG produced water has several possible uses, depending on its quality, quantity and level of treatment, including:
- supplying local farmers and communities
- irrigating crops or forestry plantations
- replenishing weirs and dams, or restoring flows in rivers exposed to heavy irrigation demand
- recharging aquifers.
- dust suppression
- industrial purposes such as drilling, coal washing, power station cooling.
All produced water is considered for beneficial use. How it is used depends on local needs and priorities.
The figure below indicates where most CSG water is used:
In Queensland, when a CSG company produces water from coals (including the Walloons) for beneficial use, a ‘Beneficial Use Authority’ is required from the government. There is one for irrigation and another for other purposes.
Special Authorities may also be used for specific projects. These Authorities specify what must be tested for and how often, as well as who should do the testing and which authority should receive the reports.
For irrigation use, tests include electrical conductivity, sodium absorption ratio (for soil integrity), pH (acidity) and 16 heavy metals and metalloids.
The water processing technology most commonly used by CSG operators to meet these standards is reverse osmosis. This is the same technology used to process drinking water in major cities around the world, including London, Singapore and Dubai.
There is a long history of water usage from coals, and rigorous processing and testing regimes are used when CSG companies produce this water and make it available for beneficial use. We can be confident that CSG production water processed for beneficial use meets the high standards required for our agriculture industry and regional communities.