THEY are largely silent, but they are out there - a collective of scientists and bureaucrats who, if they could, would like to give a clip behind the ears to the US Congress, circa 1987. It was then that the oxymoronic term ''clean coal'' was born, slipped into a bill as a catch-all for technologies that lowered emissions of sulphur dioxide and nitrogen oxide.
Later, of course, it was adopted for proposals to cut carbon dioxide emissions from burning coal.
Many who believe that the future energy supply will include a lower-emissions form of coal now wish the Reagan-era senators had opted for something less prone to satire. It hasn't made the task of selling what, to many people, seems a fanciful idea any easier. As one government adviser puts it: ''Clean coal has become an invitation for ridicule.''
This was underlined in one of the more memorable scenes from ABC's The Hollowmen, when the prime minister's spin doctors tried out alternatives - fast coal, green coal - before deciding to rebadge ''clean coal'' as ''smart coal''. Smart, they reason, because it means they can keep selling it to the Chinese at a healthy profit.
This level of cynicism is roughly on par with the way many people have come to see carbon capture and storage, the strategy most clearly associated with the ''clean coal'' tag.
The eye rolling has not dissuaded governments in Australia and abroad from making the technology central to their plan to save the world from the predicted ravages of climate change. It is likely to be an important part of any climate deal made next month in Copenhagen.
Disagreement over carbon capture and storage, or CCS, has opened a fissure in the environmental movement and divided opinion shapers who ostensibly want the same thing.
Take the contrast in the public positioning of Al Gore and Barack Obama. Gore says clean coal is a lie - like ''healthy cigarettes''. Obama says coal will remain a major source of energy, and CCS is needed given that fossil-fuel emissions are projected to continue to grow exponentially.
Is Gore a hopeless idealist and Obama a realist? Or Gore the realist and Obama - who has said reliance on fossil fuels hurts the US economy and wants permanent tax credits for research into clean solutions - hostage to a job that requires him to keep all options open, especially those vital for support in Midwestern coal states?
The most compelling argument for CCS is that the roll-out of coal-fired power in major developing economies is, for now, unstoppable. Federal Energy and Resources Minister Martin Ferguson says China will build the equivalent of Australia's coal-fired power capacity 34 times over in the next decade. The most compelling argument against CCS is that it doesn't exist, and it won't come about in time to make emissions cuts at the pace scientists say is needed.
The Global Carbon Capture and Storage Institute, created by Prime Minister Kevin Rudd and backed by $100 million from the Australia Government, has what is seen as an ambitious goal of 20 commercial-scale plants being developed by 2020. The International Energy Agency recently estimated this would not be enough - that limiting global warming to 2 degrees would require 100 plants by 2020, 850 by 2030 and 3400 by 2050. Yet a Global CCS Institute audit released last week found there were only seven commercial-scale projects worldwide. None were on coal-fired power plants, though the survey missed at least one example: a plant in West Virginia that last month started a project to capture and bury 1.5 per cent of its emissions.
The biggest barrier to CCS working is not, as most people assume, the science, but the cost. Researchers say the technology - capturing carbon dioxide either before or after combustion, transforming it into a liquid under intense pressure and injecting it kilometres beneath the earth's surface - is ready. But the Global CCS Institute estimates even the cheapest version of the technology is unlikely to be viable for a commercial project before carbon dioxide emissions cost $60 a tonne. According to Treasury estimates, this won't happen until about 2030. The institute says CCS will increase electricity prices by up to 78 per cent.
These are little more than informed guesses, based on brave assumptions about a technology that doesn't exist and a carbon market still in its infancy. Meanwhile, critics say, every billion dollars spent chasing a dream of low-emissions, coal-fired electricity is a billion dollars not spent on developing clean alternatives - solar thermal, geothermal and, more contentiously, nuclear.
One of the fears that will raise its head as CCS projects develop is the risk of fatal gas leaks. The commonly cited doomsday scenario occurred in Cameroon in 1986, when the stagnant Lake Nyos became saturated with naturally occurring carbon dioxide. The gas was released suddenly, asphyxiating 1700 people. Sceptics say CCS sites will dot the planet with potential hazards such as this that have to be managed for centuries, and that long-term guarantees of safety are virtually impossible. But Lincoln Paterson, CSIRO theme leader for CCS, says disasters due to leaks are highly unlikely. ''At a properly selected and monitored site, there should not be concerns,'' he says. ''You wouldn't try to store [carbon dioxide] under a deep, stagnant lake.''
Carbon Storage Taskforce chairman Keith Spence says people wrongly believe CCS involves just dumping gas in caves. ''In fact, it is like putting it into a sponge. If a seal did actually leak, it would leak very slowly,'' he says.
The Australian and Victorian governments are unashamedly in the pro-CCS camp, on the basis that it is necessary for the world's wellbeing and important for Australia's economic strength. Ferguson says it is ''increasingly clear that no serious response to climate change can ignore the need to accept fossil fuels as part of our shared future''.
Victoria will put CSS at the centre of its future energy statement, due to be released later this year. All evidence suggests that, if CCS is to prove viable, the state is exceptionally placed to be a world leader in its development. A national Carbon Storage Taskforce commissioned by Ferguson has produced a costed infrastructure plan for transporting the carbon dioxide to suitable basins. It is yet to be released, but it is understood the taskforce has confirmed that Gippsland Basin has A-grade potential, with highly porous rock, a seal that is considered impenetrable and the capacity to store all of Australia's emissions.
Uniquely within Australia, the Gippsland Basin - which runs along Victoria's south-eastern coast, about two-thirds offshore and the rest under Gippsland itself - is also close to the source of power generation. This proximity would dramatically cut storage costs.
It is believed the taskforce report suggests low transmission costs could make CCS viable in Victoria 10 years before other parts of the country.
Already, Victoria is at the centre of Australia's limited, fragmented work on CCS. None of its projects combine capture and storage. The country's only storage demonstration project is in the Otway Basin, where a little more than 60,000 tonnes of carbon dioxide has been injected into a depleted gas field.
Hazelwood power plant, often described as Australia's dirtiest, is trialling a capture plant that removes about 0.05 per cent of its emissions after combustion. Loy Yang A has a pilot capture project run by the CSIRO. A separate project at Mulgrave is run by the Co-operative Research Centre for Greenhouse Gas Technologies. In all cases, the quantities are tiny.
In Queensland, the Government and coal industry have jointly backed ZeroGen, with aims to use integrated-gasification-combined-cycle technology, turning coal into gas, and eventually capturing 90 per cent of emissions. On the other side of the country, Chevron, Shell and Exxon plan to inject 125 million tonnes under Barrow Island as part of the Gorgon LNG project. It is billed as the world's largest for carbon sequestration.
These are ultimately only baby steps. Given the price challenges, it is widely acknowledged that CCS will need substantial government backing if it is to succeed.
The Rudd Government's answer has been a $2.4 billion fund to cover a third of the cost of building up to four commercial-scale CCS ''flagship'' projects. Comparatively, the flagships program for large-scale solar power announced in this year's budget is worth $1.5 billion.
Tony Maher, general president of the CFMEU and a member of the Carbon Storage Taskforce, says the investment in CCS is a reasonable step. ''Not enough has been done, it's as simple as that,'' he says. ''I don't think there is a valid argument that, well, you shouldn't start. You need to build these things and make an assessment, and they will make an assessment after they've built not one but three or four. The global assessment, I presume, will happen after they've built 20, and then the task is really judging how it stands up compared to other emerging technologies.''
Others are less impressed. Environment Victoria campaigns director Mark Wakeham says governments show incredible optimism about the ''leap of faith'' that is CCS, but are lukewarm about many renewable energy possibilities. ''It is mesmerising governments, attracting huge amounts of public funding and delaying investment and focus on genuinely clean industries that are ready to reduce emissions,'' he says.
Environmentalists, unions and other observers are united in their condemnation of the lack of research into CCS by coal-reliant industries. A recent report by WWF Australia and the CFMEU found the coal industry had committed only $513 million to the Coal21 project to develop low-emissions technologies.
Beyond investment, advocates say CCS will depend heavily on its inclusion in the ''clean development mechanism'' of a new climate treaty, allowing wealthy nations to earn credit by building plants in the developing world. Australia is pushing for its recognition at Copenhagen.
In theory, the emissions trading scheme will also push it along. The Treasury says CCS is likely to be viable shortly after 2030, though observers have questioned how it arrived at this conclusion. Richard Denniss, of the Australia Institute think tank, says the Treasury stance - that Australia would start building commercial CCS plants in 2033 and have a full fleet a decade later - is the equivalent of saying ''Santa Claus has to exist''. ''The modelling doesn't prove that CCS will be viable, it just assumes it,'' he says. ''For all [Climate Change Minister] Penny Wong's talk about transforming the technology and market-based mechanisms, their strategy hinges on a silver bullet of cheap, clean coal.''
Whether this is justifiable optimism based on our capacity to find solutions or culpable wishful thinking, with the ramifications to be felt by future generations, only time will tell.