A small contribution the Nukes vs. Renewables debate on Max's blog.
http://maxspeak.org/mt/archives/002157.html#more
***************** Cheers Gar. Good piece. Nuclear power is becoming a BIG issue down here, as Australia contains scads of uranium, a lot of which is in Western Australia, where I live. Fortunately, the Labor Party in WA still has a policy in force not to mine uranium, but they're being pushed and shoved a lot on this issue and will probably cave soon. But, in terms of the whole Global Warming debate, something else has to be done....see for example:
http://www.abc.net.au/rn/science/ockham/stories/s1613742.htm
This Emeritus Professor John Veevers (below) makes good sense to me and touches on a non-carbon based power source which may have application on other parts of the planet.
Happy 20th to the Chernobyl Disaster, Mike B)
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..As it happens, Australia has a way out. We are well endowed with a safe no-emissions solution in a vast hot fractured rock resource beneath the Innamincka area of Central Australia. About 320-million years ago, molten granite with enhanced abundances of radioactive elements rose up from the depths. By 20-million years later, after it had cooled, the granite was unroofed by erosion, and its surface sculpted by glaciers. During the unroofing, natural cooling fractures expanded and filled with water. The granite was then blanketed by river and lake deposits of shale, coal and sandstone that now contain the natural gas of the Cooper Basin. Later still, the region was covered again by river deposits that now form part of the Great Artesian Basin. Nature has brought together in one place a huge body of hot fractured granite with its insulator of gas-and water-bearing sedimentary rocks at a depth within reach of current drilling technology. It is this geothermal resource that the Australian company, Geodynamics Limited, has recently started tapping with great promise of success.
The Earth is hot: all but the outermost shell is hotter than 1000 degrees, and the core is 5000 degrees. Some of this is fossil heat from the beginning four and a half billion years ago when the earth accreted from rock, dust and gas into a molten ball. Most comes from the slow radioactive decay of uranium, thorium and potassium that became concentrated in continental crust. If it wasn’t for this radioactivity the earth would have cooled to a dead planet several billion years ago and life would be very different. Land masses may not have existed above the watery surface, and what then of humanity? But that’s another story.
Granites with as much as 4% potassium, 50 parts per million thorium, and 20 parts per million uranium generate about 10 microWatts of heat per cubic metre continuously for hundreds of millions of years. If hindered from escaping by an insulator, the heat accumulates to a degree that can be exploited for generating electricity. The average temperature increase towards the interior of the crust is about 30 degrees per kilometre making a temperature somewhat less than 150-degrees at a depth of 5 kiliometres. This temperature increase is why deep mines are air conditioned: without it, miners would fry. In the hottest part of the Cooper Basin, the gradient is 60-degrees per kilometre or almost 300-degrees at a depth of 5 kilometres, nearly double the average.
Heat from the radioactive isotopes uranium 238 and 235, thorium 232, and potassium 40, has brought the granite at a depth of 4 kilometres to a temperature of 250 degrees. As in oil and gas exploration, we need to store the resource in a reservoir and to contain it by a cap or seal. At Innamincka, the reservoir is made by opening the natural horizontal cracks or fractures by pumping high-pressure water into the granite. The natural horizontal shearing stress in the crust then shifts the roof of every crack sideways so that it slips a few millimetres When the water pressure is released, the cracks close but do not mate. The minute sideways slippage brings a ridge above against a ridge below and the permeability along the fracture systems increases a thousandfold. That means that water can now circulate through an engineered plumbing system to make an effective heat exchanger. The network of water-filled cracks becomes the heat reservoir. And the heat is kept in by the 4-kilometre thick sedimentary rocks above.
Geodynamics have drilled tow holes 500 metres apart, 4500 metres deep, and penetrating 700 metres into the granite. Water pumped down the injection hole percolates through the engineered reservoir in the hot rock and flows into the production hole. At the surface, the superheated water will be led through a conventional heat exchanger to generate electricity. The system is a closed loop and doesn’t require a large water supply. Indeed the water found in the fractured granite will probably be sufficient for this purpose.
The geothermal resource extends over 1000 square kilometres. With one hole per square kilometre, and 40 holes per year, the resource would be fully developed in 25 years, initially taking up the extra demand for electrical power before phasing out coal-fired power stations altogether. Based on the energy released by reducing the temperature of the top 1000 metres of the hot fractured rock by 100 degrees, the resource is calculated to be equivalent to 50-billion barrels of oil, or one-fifth the oil reserves of Saudi Arabia, or 12 times the gas reserves of the North West Shelf, or 60 times bigger than the Snowy Mountains Hydro-Electric Scheme. This is enough to supply without emissions the base-load electrical power at current levels of all consumers in Australia for 70 years. Modelled costs are 4 cents per kilowatt hour, plus a half to one cent for transmission to the grid. This compares with 3.5 cents for black coal, 4 cents for brown coal, 4.2 cents for gas, but all with uncosted emissions. Clean coal, the futuristic technology of coal gasification combined with CO2 sequestration or burial, yet to be demonstrated, comes in at 6.5 cents, and solar power and wind power a 8 cents.
The Innamincka hot fractured rock project is a known geothermal resource, large in scope, high in temperature, and exploitable by conventional technology. The trick will be to scale the project up to its potential. The surface will not have its tranquillity disturbed beyond hosting clean generators and transmission lines. This kind of resource is rare but not unique, and Australian enterprise could well lead a global revolution. An international Oz Rock Power Corporation could overtake General Electric as the leading global company.
Back on our part of Earth, the promise of abundant clean power has been bankrolled by $60 million from the Stock Market, now trebled to a capitalisation of $175 million, I declare a modest interest, and a grant of $6.5 million from the Commonwealth. Geodynamics are now seeking a piece of the $500 million Low Emission Technology Fund. Tapping this resource of course, transcends the mere commercial. This project should be this generation’s national project as the Snowy Mountains Hydro-electric Scheme was for the post-war generation. Governments should not be leaving geothermal power to the market; this is a national responsibility. But even on a narrow economic basis, governments should invest now in geothermal power instead of building new coal-fired power stations. At the current cost of coal and with carbon credits, a fully-costed power station at Innamincka will break even with any new coal-fired power. The enormous environmental benefit will be a bonus.
full: http://www.abc.net.au/rn/science/ockham/stories/s1440622.htm
Read "Penguins in Bondage": http://happystiletto.blogspot.com/
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