The truth about... 'clean coal'

Winning an Oscar and a Nobel Prize ought to be enough for Al Gore -- never mind the two terms as US vice president. But yesterday he set his ambitions higher still, aiming to convince the United States to end its reliance on polluting sources of energy, in a drastically short space of time. In a speech last week in Washington, he explained why: “The survival of the United States of America as we know it is at risk. And even more – if more should be required – the future of human civilization is at stake.” He compared his challenge to the Apollo programme that put man on the moon, and set a similar deadline to accomplish his goal: a decade.

He spoke of solar and wind power, energy conservation and better transmission systems. But he also alluded to another technology he discussed two years ago during a speech to NYU law school : ‘clean coal’, as it has come to be known.

From the point of view of carbon emissions, the phrase seems an oxymoron. Coal is more or less pure carbon, and burning a tonne of it produces around three tonnes of CO2.  It can be made to burn more efficiently (so that less is mined and burnt to produce a given unit of energy), and other pollutants such as sulphur and particulates can be filtered out. But the problem of what to do with the CO2 remains.

One solution would be to pipe the gas back underground -– a process known as carbon capture and storage (CCS). In theory, this is a wonder-technology: the world can continue to use a fuel which already provides the majority of its energy needs and which can be found in huge quantities in politically-stable countries. Coal is reliable (unlike wind and solar power), safe (unlike nuclear fission) and proven (unlike nuclear fusion). If its environmental impact can be dealt with, coal offers a solution to the world’s energy needs for centuries. No wonder politicians such as US President George Bush have leapt on the technology.  

However, recent reports pose grave doubts as to the viability of the technology. Even industry representatives accept that it will be 2020 at the earliest before the technology is in commercial operation, with academic studies putting the date closer to 2030. Even then, the technology looks to be expensive, and not particularly clean:

• CO2 needs to be removed from the coal, either before it is burned or from flue gases, and piped over a kilometre underground in order that it stays liquid. Moreover, the right kind of rock formations must be in place to keep the gas in place for millennia -- and these are not always close to power stations. A new infrastructure of CO2 transportation -- a ‘reverse oil industry’ -- would be required to get the waste gas to its final home.
• Once the gas is in the ground, it may seep out -- either gradually, or very dramatically after an event such as an earthquake (a natural CO2 eruption in Cameroon’s Lake Nyos in 1986 killed 1,700 people). The necessary geological research is still in its infancy, and predictions may not be accurate. As with nuclear waste, the issue of who is responsible for the gas once it is in the ground is unclear.
• Lastly, clean coal is not a carbon-neutral activity -- present carbon capture technology only removes around 85 per cent of emissions, at a cost of 10-40 per cent of energy generated. Mining and transporting millions of tonnes of coal creates a huge carbon footprint of its own.

Why, then, are politicians so keen? To cynics, talk of ‘clean coal’ allows politicians to authorise polluting plants and leave to others the problem of their emissions. Those cynics might use as ammunition the US Department of Energy’s decision in January to withdraw funding for a CCS testbed power plant, one day after Bush emphasised clean coal in his State of the Union address. At present it is political reputations, rather than coal flues, which are getting scrubbed.