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| Fig. 1: Australia's crustal temperature at a depth of 5 kilometers. [4] (Source: Wikimedia Commons) |
As climate change and the deterioration of our ecosystem become truer every day, it is clear that renewable energy is the future. When thinking of renewable energies in Australia, people immediately think hydro power and wind power because those are their two largest renewable energy industries. However, Australian entrepreneurs and the Australian government have recently been conducting research and explorations to tap into the country's geothermal potential. As of now, it is estimated that converting just 1% of Australia's hot rock energy to electricity could supply Australia's energy production for 26,000 years. [1] With potentials like that, it is clear why the Australian government is heavily invested in pursuing this form of renewable energy.
Geothermal energy is the energy stored as heat in the earth. Heat from the earth's crust warms water that has seeped into underground reservoirs over time. When the water becomes hot enough, it breaks through the earth's surface as hot water or steam, allowing it to be harnessed as energy. Geothermal energy is one of only a few resources that is inexhaustible, having the potential to power a significant share of Australia's energy needs. [2]
Currently in Australia, there are two types of geothermal energy under development. The first type under development is enhanced geothermal systems (EGS) where the heat stored in rocks deep beneath the earth's surface is fractured to create reservoirs. Wells are drilled at depths between 3-5 kilometers to find heat-producing granites. Water is then pumped into these wells through the fractured rock where the water becomes heated up to temperatures of 300°C. The scalding water is then pumped back to the surface where the heat is used to drive a turbine and produce electricity. [3] The second type of development underway is hot sedimentary aquifer (HSA) geothermal energy. HSA systems are generally developed in shallow, porous sandstones containing water that is heated by either hot rocks or crustal heat flow. Since HSA is at shallower depths, it is cheaper than enhanced geothermal systems. [3] Between 2002 and 2013, it is estimated that just over $1 billion was spent on studies, geophysical surveys, drilling, and reservoir tests looking at EGS and HSA systems. Currently, over 380 geothermal energy projects have applied for licenses to begin development. [1]
Fig. 1 shows Australia's crustal temperature at 5 kilometers. Australia is unique in the sense that it is an enormous island with an extensive granite layer underneath the surface. This layer manages to heat up to perfect geothermal temperatures of more than 400°F. [1] The almost inexhaustible supply of heat beneath the largely arid island of Australia is waiting to be harnessed, with intense hotspots in Perth, Northern Australia, and Southern Australia.
With non-renewable resources like gas and coal deteriorating our ecosystem, non-renewables like geothermal are necessary to ensure sustainable energy for the future. While Australia is very new to the geothermal energy game, it is clear that they are making solid headway. With hundreds of projects going through the approval process and gaining funding, Australia's geothermal energy sector is sure to grow exponentially.
© Jack Barber. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] B. A. Goldstein et al., "Hot Rock Geothermal Energy Plans in Australia," Commonwealth of Australia, Geoscience Australia, 9 Feb 09.
[2] "Geothermal Basics: Q&A," Geothermal Energy Association, September 2012.
[3] D. Brown, "A Hot Dry Rock Geothermal Energy Concept Utilizing Supercritical CO2 Instead of Water," Los Alamos National Laboratory, 24 Jan 00.
[4] M. W. Hayes et al., "TherMAP - Assessing Subsurface Temperatures in Australia From a Geothermal Systems Perspective, Commonwealth of Australia, Geoscience Australia, 19 Apr 15.