Lake Eyre Basin Rivers 188 Although some call the emergence of shale gas an ‘energy revolution’ or even a ‘game changer’, critiqued by Hughes (2013), potential environmental and public health impacts make it highly controversial (e.g. Jackson et al. 2013 Small et al. 2014). This also uses hydraulic fracturing (‘fracking’) of the shale to increase permeability and allow water, gas and petroleum liquids to flow from where they are trapped. Given the vast size of shale rocks across continental platforms, such as the Marcellus Shale in the eastern United States, this represents an enormous energy resource. The hydrocarbon liquids produced by shale gas activities attract the oil price, and this value is deducted from the costs of gas extraction. A high oil price makes gas cheaper to produce, although the recent decline in the oil price has reduced this effective subsidy and now makes some shale gas operations marginally economic to uneconomic. There are significant environmental and health risks and potential impacts, although there are relatively few scientific studies (Drinkwater et al. 2014). First, shale gas and fracking may increase methane (and possibly other contamination) into shallow groundwater resources, sometimes important for drinking water. The most infamous example is the lighting of methane from a kitchen tap in Colorado, burning continuously due to the high methane content of the water (popularised by the documentary movie Gaslands by Josh Fox). The two common ways which could explain this outcome are either faulty construction of wells, allowing methane to migrate along this pathway to shallow (less than 100 m) groundwater (Osborn et al. 2011 Jackson et al. 2013) or fracking causing connection of vertical fractures between shale gas and overlying groundwater systems. This is not widely accepted for deep shales (2–3 km) but may be a problem for shallow shale gas operations. Second, some chemicals used in fracking are highly toxic, such as biocides used to control unwanted bacterial growth, which can seal the fracture and reduce permeability. These chemicals have seldom been subjected to rigorous environmental risk assessments for use in fracking. This is especially relevant for CSG, which is often much shallower, 0.5–1 km, than shale gas. Third, there are increased risks of seismic activity (i.e. earthquakes) from fracking, often relating to low intensity but increased frequency, although this may be more related to deep injection of wastewaters (Small et al. 2014). Fourth, concerns over or competition for water and land between gas companies and agriculture can be significant (Drinkwater et al. 2014). Fifth, increases in air pollution, especially volatile hydrocarbons and noise, could explain impacts raised by local communities near shale gas activities, although still poorly understood (Drinkwater et al. 2014). Sixth, formation waters extracted from shale gas operations are often saline and may be rich in hydrocarbons and/or heavy metals, including sometimes radioactive elements such as radium or uranium (Barbot et al. 2013), leading to major wastewater management issues. Finally, discussion about the relative merits of investment in renewable energy, compared to shale gas development, is seldom debated. Shale gas production remains a deeply contentious industry. Despite high profile claims of a potential shale gas bonanza in the Arckaringa Basin (Fig. 19.1), there remain no reported shale gas reserves yet in or near the Lake Eyre Basin. Rare earths The rare earth group of elements, often called rare earth oxides, their typical form in nature, are increasingly critical for a range of modern technologies. They are essential for computers,
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