"One hundred percent renewable energy in Australia by 2020!" That was the bold call endorsed by members of more than 150 climate action groups at the Climate Action Summit held in Canberra in January.
By and large, the establishment media have ignored this call — or else dismissed it as green "extremism".
Renewable energy sources are said to be incapable of replacing fossil fuels, especially coal. They can't supply 24-hours-a-day "base-load" power, say most media commentators.
Not only that, the argument continues, but renewable energy is still too expensive — about $70 per megawatt-hour for wind power, currently the cheapest. In contrast, it costs about $45 for natural gas and $35 for black coal.
Rarely, is it acknowledged that geothermal energy also provides constant, day-and-night power. But the technology needed to generate electricity from Australia's geothermal resource, we are told, is unproven. And the geothermal fields themselves are too remote to be exploited in the near term.
Coal, the message goes, is here to stay.
These arguments are half-true at most. When dispersed over thousands of kilometres, wind farms are perfectly able to supply base-load power.
Australia's main sources of geothermal energy are distant from the electrical grid, but others lie beneath existing high-tension power lines.
The "hot dry rock" (HDR) technology needed to extract most of the country's geothermal resource is indeed new. But it is well past the experimental stage; elsewhere in the world, pilot plants have been using it successfully for years.
In any case, Australia has now been shown to have substantial resources of conventional "hot wet rock" geothermal energy, conveniently sited in western Victoria and south-eastern South Australia. The technology for conventional geothermal is fully mature.
Conventional geothermal is among the cheapest of all energy sources, fossil or renewable. Modelling from firms working on HDR geothermal, meanwhile, show the costs of the electricity produced should be about the same as for gas-fired base-load plants.
So why the tepid response to geothermal energy? Might it have something to do with the immense political clout of the coal industry, fearful of a clean, low-cost competitor?
Australia could easily be the Saudi Arabia of geothermal energy.
Thick beds of granite, covering about a thousand square kilometres, lie deep under the Eromanga Basin covering south-west Queensland and north-east South Australia.
Above the granite lie sedimentary rocks. In South Australia's Cooper Basin area these rocks are host to Australia's main onshore oil and gas fields.
Decades ago, drillers for oil and gas in the Cooper Basin noted astonishing temperatures at the bottom of their holes.
As radioactive elements in the underlying granite decayed and released heat, the rock above was acting as an insulator, allowing temperatures to build up. The highest temperature so far measured is 287ºC at 5000 metres below the surface.
Could this heat be extracted, geologists and engineers wondered, by injecting water and using the resulting steam to produce electricity?
This concept has now been proven at several sites in Europe. In July 2008 the New Scientist reported: "The first 1.5-megawatt power station at Europe's experimental [HDR geothermal] plant in Soultz, France, will soon begin operating continuously, and a second 3-megawatt ... power station in Landau, Germany, is already selling electricity."
HDR geothermal has been shown to work, but what are the prospects in Australia?
The April-June 2008 issue of ReNew cited a study, "using conservative assumptions", which said potential reserves of geothermal energy in Australia came to "23 million petajoules ... or 7500 years of Australian energy consumption at the current level".
Over 80% of this resource was reported to be in the Eromanga Basin.
Just one geothermal project now being developed by the firm Geodynamics near Innamincka in South Australia has been rated as equal to the yearly energy output of 20 Snowy Mountains schemes.
Geodynamics plans to eventually build 10,000 megawatts of generating capacity on its Innamincka site. This would equal about 20% of Australia's current generating capacity, or about half of base-load demand.
A one-megawatt demonstration power plant was due to begin generating electricity by the end of April. A 50-megawatt plant is planned for 2011.
Naturally, there are hurdles still to be crossed with geothermal power. In theory, cost should not be one of them.
Modelling carried out for Geodynamics in 2005 said that a 300-megawatt geothermal plant at Cooper Basin could produce electricity at $40 per megawatt-hour. A 1000-megawatt plant might undercut the price of coal-fired power.
The economics of geothermal energy will benefit from falls in drilling costs, which are declining in real terms by about 1.5% a year.
In 2008, a report prepared by consultants McLennan Magasanik Associates for the exploration company Petratherm forecast that by 2050 the cost of geothermal electricity would fall to about $32 per megawatt-hour, compared with $55 for "nuclear new design" and $58 for an advanced coal-fired plant with carbon capture and storage.
But the main costs of geothermal energy, unlike coal power, have to be paid up front. These start-up costs are not small.
A 300-megawatt generating plant, Geodynamics says, would need 37 wells on an area of seven square kilometres. Such wells cost between $10 million and $15 million each.
At a time when banks are refusing to lend even to each other, private financial institutions are not lining up to fund geothermal energy.
Then there is the need for power transmission infrastructure.
The Geodynamics site near Innamincka is about 490 kilometres from the nearest grid connection. New high-voltage transmission lines cost between $1 million and $2 million per kilometre.
Meanwhile, the logistics of drilling the hundreds of wells needed for really big geothermal developments are challenging.
There are only two rigs in Australia designed for drilling onshore to depths of 5000 metres and beyond. More machines will have to be imported at a cost of more than $30 million each, with orders placed many months in advance.
None of these problems are unbeatable. The underground heat is there — as much of it, effectively, as Australian capitalism cares to extract.
Can the system summon the political will and environmental scruple to go hard at the task of replacing coal-fired base-load power with geothermal in a decade?
A strategy for geothermal
Before answering this question, we need to map out a general strategy for coming up with at least 20,000 megawatts of geothermal power at a rapid pace.
There is a crucial need for drilling equipment. Buying licenses where necessary, but also beginning a big research and development effort, Australian industry needs to come up with world's best rigs and other technology for drilling into deep granites.
Then there is the need for transmission infrastructure. Last year, Geodynamics lobbied for the construction of a "transmission superhighway" linking Adelaide and Brisbane, with its hub in the geothermal fields of the Eromanga Basin.
The idea is a valid one. The line could use high-voltage direct current technology that loses only about 3% of current every thousand kilometres.
The line would connect up promising geothermal fields at Paralana and Callabonna, to the east of the North Flinders Ranges.
As specialised drilling equipment became available, HDR geothermal exploration work could be stepped up, largely in the Eromanga Basin but also at sites close to existing power lines.
At one such site, north of Port Augusta, temperatures have been estimated at 240ºC at 5000 metres below the surface.
Much of the early geothermal development, however, would be conventional geothermal.
Resources of this kind are known to exist beneath wide areas of western Victoria, as well as in South Australia near Renmark and Penola, and on the Limestone Coast.
The Limestone Coast geothermal resource has been described as having "an estimated generating potential of approximately 1500 megawatts ... enough power for more than one million homes." A 4.5-megawatt demonstration plant is planned for late in 2011.
In western Victoria, the Age said on January 10, "vast aquifers of ancient brackish water heated up to 145 degrees" lie beneath sedimentary rock at depths between 2.4 kilometres and more than four kilometres.
One of the exploration firms involved "believes there is enough geothermal power available within its tenements to generate up to 5000 megawatts, or almost Victoria's entire electricity requirement."
At these relatively shallow depths, highly specialised drilling equipment would not be necessary.
Renewables and capitalism
Could a concerted push to develop geothermal energy provide the base-load power needed to replace coal-fired power by 2020?
Much of the necessary engineering capacity could be freed up if Australia's "defence" complex were converted to useful production.
As for the start-up costs of geothermal power: if Australia were suddenly found to be a Saudi Arabia of oil rather than of geothermal energy, would the money, equipment and skilled workers be found to rush the newly discovered oilfields, however remote, into production within a few years? The question answers itself.
Oil, of course, is in relative shortage, commanding handsome prices and good profits even during a recession. Meanwhile, cheap coal means that Australia already has plenty of electricity, much of it at prices HDR geothermal would not quickly match.
To really embrace geothermal power, Australian capitalism would need a profit signal pointing unmistakeably toward producing and using renewable energy.
The signal at present is very different. Switching to renewables would mean junking coal assets worth billions of dollars, while these assets were still bringing good returns.
That is not to say that coal should remain king, or that switching to renewables should not be an urgent national priority.
What it does show is that capitalism, with its tunnel-vision focus on private profit, is simply unable to bring about the changes needed to avert an environmental catastrophe that threatens to end civilisation as we know it.