Rowan Drinkwater,Science, Technology, Environment and Resources
Key Issue
The development of coal seam gas (CSG) and exploration for other unconventional gas sources has been highly controversial. This controversy is focussed mainly on environmental impacts and land access issues. This brief outlines some of the key terms and concepts underlying the debate.
What is unconventional gas?
Naturalgas is combustible gas that is formed and held in underground deposits.This gas is composed mainly of methane—up to 98 per cent—with varying amountsof other trace gases depending on how and where it is formed. Some sources ofnatural gas are called ‘unconventional’ because they are more difficult toextract and require additional technology or effort beyond that required for more‘conventional’
gas.
The different types of unconventional gas, and thenaming conventions, vary depending on their geological origin.There are three main types. CSG—orcoalbed methane—is found in shallow coal seams. Tight gas is found in sandstonelayers that are not sufficiently porous—or too ‘tight’—for the gas to flowthrough and hence trap the gas. Shalegas is found in shale layers (see Figure 1).
Unconventional gas production, almost exclusivelyfrom CSG, from 2011–12 accounted for about 13 per cent of all gas production inAustralia.
Figure 1: The geology of natural gasresources
Source: US Energy Information Administration website
Australia’s main CSG projects are located in Queenslandand NewSouth Wales (see Figure 2). There are also significantpotential volumes of shale and tight gas, across allstates and territories except the ACT, with the largest basins located inWestern Australia, the Northern Territory and in the Cooper Basin, which straddlesQueensland and South Australia. States and territories are all at differentstages in developing their regulatory frameworks for shale and tight gas, butthese industries are still emerging, with preliminary exploration currentlyunderway.
How is it different to conventional gas?
From a consumer perspective unconventional gas mayseem practically identical to conventional sources of natural gas, but thereare a few important differences.
Most sources of conventional gas are locatedoffshore, while many onshore sources are not located near other land users andlocal communities. In contrast, CSG developments are often close to, or evenco-located with other industries, such as agriculture. In addition CSGdevelopments can be located close to regional towns and cities.
Figure 2: Australia’s coal seam gasreserves—in petajoules (PJ)—and associated infrastructure
Source: Office of the Chief Economist, Review of the socioeconomic impacts of coal seam gas in Queensland 2015
Co-location at times has resulted in conflictbetween landowners and resource interests.
In addition, the extraction of unconventional gas typicallyrequires more wells and more access roads and pipelines. This means more landis needed than for conventional gas developments. Significant volumes of waterare also produced through the CSG extraction process. This water contains saltsand other contaminants that need to be treated at the surface and used ordisposed of appropriately.
For shale and tight gas, hydraulic fracturingis usually required to enable gas production. Hydraulic fracturing is a processwhere fluid and sand is injected at high pressure in order to re-open naturalfractures and create pathways for gas to flow.
Hydraulic fracturing, or ‘fracking’, has becomesynonymous with CSG production. However, this is somewhat of a misnomer, as frackingis not always used in CSG production in Australia. Of all the CSG wells inAustralia, fewer than 10 percent have been hydraulically fractured, but this number may increase overtime. Hydraulic fracturing also requires significant volumes of fresh water—typicallyin quite dry areas—which can present its own challenges and risks.
Consequently, these projects can often be morecomplex and costly than conventional gas ventures.
Why were these resources developed?
In Queensland, gas production from the two main CSGbasins—Bowenand Surat—beganin 1998 and 2005 respectively. Production from these sources began in part as aresult of the reduction of conventional gas production from existing fields.
The production also coincided with a Queenslandgovernment policy in place at the time that required upto fifteen per cent of electricity to be sourced from gas-fired generation.This policy, in part designed to reduce the state’s greenhouse gas emissions, alsohelped create a fixed gas demand in the initial stages of development. Laterexpansion of the CSG industry has been due primarily to the Liquefied NaturalGas (LNG) export market. The high export value of LNG also precipitated theexploration of shale gas resources in other states.
Risks and concerns
There have been a numberof concerns raised about the risks of unconventional gas developmentincluding: human and environmental health impacts, threats to water resources,air quality concerns, land use competition and social impacts.
Comparing the impacts observed in Australia withoverseas industries is challenging because of the influence of local conditionson the potential risks. However, issues around well integrity, environmentaland human health risks as well as more general concerns have been found to besimilar.
The scarcity of baseline environmental data has alsohindered efforts to understand the potential impacts of CSG developments andestablish causal links between certain activities and observed impacts. Researchinto these impacts and their management is continuing.
The water trigger and the IESC
The regulation of onshore gas resources is primarilythe responsibility of states and territories. However, in 2013, the AustralianGovernment amended the Environment Protection and Biodiversity ConservationAct 1999 to require CSG and large coal mining developments to obtainCommonwealth approval where they would have a ‘significant impact’ on waterresources. This is known as the ‘watertrigger’.
This Commonwealth approval is separate to stateapprovals and must take into account advice from the Independent Expert ScientificCommittee on Coal Seam Gas and Large Coal Mining Development (IESC). Futureshale gas or tight gas projects in Australia will not be regulated under thistrigger as it only applies to CSG and large coal mining developments. The watertrigger is currently under review.The review report was due to the Minister for the Environment by 31 March 2016.
Further reading
M O’Kane, Final Report of the Independent Review of Coal Seam Gas Activities in NSW, New South Wales Chief Scientist and Engineer, Sydney, September 2014.
Department of Industry, Innovation and Science, Energy in Australia 2015, Canberra, January 2016.
Select Committee on Unconventional Gas Mining, Interim Report, Canberra, 4 May 2016.
R Drinkwater, ‘Coal Seam Gas: the Commonwealth's regulatory role’, FlagPost, Parliamentary Library blog, 13 July 2016.
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