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Credit: Photolibrary MODERN SOCIETY is totally dependent on reliable energy sources. In particular, we're addicted to fossil fuels. But while media discussion of our energy options is often framed in terms of fossil fuels versus green renewable sources, such as wind and solar, in Australia another abundant energy source lies right beneath our feet. The Earth is effectively a heat engine, and much of its geological activity is a consequence of heat loss from the deep interior. This heat comes from the decay of naturally occurring radioactive elements like uranium, thorium and potassium, as well as leftover energy from the processes that formed our planet. Unusually enriched Heat flow near the Earth's surface is generally highest at mid-ocean ridges, and lowest in areas of old continental rock. But surface heat-flow records in Australia show much higher than average heat throughout the continent's centre: western Queensland, the Northern Territory and South Australia, as well as parts of western Victoria. In the southeast of this zone, the heat is linked with recent volcanic activity around Portland and Mount Gambier, but elsewhere it comes from high concentrations of radioactive heat-producing elements. This occurs mainly in Mount Isa, Pine Creek, central Australia and the northern Flinders Ranges, in rocks around one to two billion years old. In these regions, rocks can have concentrations of radioactive elements 10 to 15 times higher than expected for their age. There are few similarly enriched rocks in other parts of the world (particularly for uranium), and nowhere near the vast volumes of enriched rocks we have in Australia. This bounty of heat-producing elements represents a vast energy source that has enormous potential to generate both geothermal and nuclear power in Australia. If we engage in debate on our energy future without considering this, then we will sorely miss out. Vast resource Nuclear and geothermal power in Australia are intimately linked, arising from the same geochemical enrichment of heat-producing elements. Indeed, despite the amount of attention the local geothermal power industry is starting to receive, it's not well appreciated that this low-emission heat source arises, ultimately, from uranium. Geothermal power plants work by pumping water to depths of three to five kilometres where rocks reach temperatures of up to 300°C. The heated water returns to the surface as steam which is used to rotate turbines and generate electricity. Conventionally, the high sub-surface temperatures required come from volcanic activity. New Zealand and Iceland exploit this to generate inexpensive and abundant energy: the fresh produce available year round in snow-covered Iceland is grown in greenhouses heated by geothermal power. Readers' comments
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Uranium, The Last non-Renewable Fuel
Australia is also one of the richest sources of renewable and clean solar energy! Once Science and technology find a way to separate Hydrogen from water effectively, and combine with it carbon, preferably from the atmosphere, to make a liquid fuel, like diesel, a non flammable, clean burning, non-corrosive, high energy fuel for our beloved piston engines, Solar will be the king of fuels. The remaining Uranium in the world can be used to establish the 'seed' solar plants that will eventual take over except in those cases, like ice-breakers and submarines, where Uranium will reign supreme. Recycling spent reactor fuel is another area of interest. McGill University, in the mid 1950's developed a low-grade fuel reactor called the 'Slow Poke', and then stopped moving in that direction. The urgent quest for new energy sources in the world today may rekindle interest in methods of extracting usable energy even from low grade 'spent' reactor products, to extend the useful life and mitigate the safe storage problems associated with Uranium as a fuel.India has a Thorium reactor planned that does this quit well, and China will soon show its scientific prowess and possibly show the way to the energy future. American schools are underfunded repositories for the entitled, not necessarily the 'smart' part of their population and have fallen by the wayside in Science and Technology. We can expect less from them than in the past.