Can ‘clean coal’ save the world?

What is clean coal?
An oxymoron... for now. Coal is still what it always was: cheap and dirty. The most carbon-intensive fossil fuel, it accounts for nearly 40 per cent of the world's CO2 emissions, yet its use is rising, not falling. Coal-fired power stations provide 41 per cent of the world's elec-tricity, a proportion forecast to rise to 44 per cent by 2030. With the huge increase in energy demand, the amount of electricity generated from coal in that same period is expected to rise 23 per cent in the US, 172 per cent in China and 258 per cent in India. If coal stays dirty, its CO2 emissions will almost quadruple. That's why 'clean coal' technology is being so urgently embraced by governments around the world.

What does that technology involve?
A process called 'carbon capture and storage', or CCS, under which a power plant's CO2 emissions are chemically diverted (or 'scrubbed') before they have a chance to escape into the atmosphere, then stored as a liquid, out of harm's way. That, in theory,  would reduce the quantity of CO2 emitted by as much 90 per cent. But in practice that presupposes the solving of a huge problem associated with CCS - where to store all those emissions.
 
What are the storage options being considered?
The two main contenders are injecting CO2 into depleted oil and gas fields or burying it in saline aquifers - porous rocks full of salty water - deep below the surface. But whatever solutions are chosen, the scale of the storage problem is daunting. One estimate says that by 2030 the US alone would have to drill more than 100,000 wells, perhaps as many as 300,000, to keep its CO2 emissions at 2005 levels. And there are still questions about how stable the CO2 would be underground. Any leakage - and green groups say that the gas would have to remain sealed forever - would defeat the whole purpose of storage.

But is the process of CCS technically feasible?
Very much so. Each of the various stages has been successfully tried, just never put together. Energy companies have been transporting and pumping liquefied CO2 into oil and gas fields for decades to help flush out precious fossil fuels. Norway's state oil company, meanwhile, has been storing CO2 in deep, off-shore aquifers since 1996. And the key bit of the process - 'scrubbing' emissions from power stations - has been operating at the world's first CCS demonstration plant in Germany since last September. "There do not appear to be unresolvable open technical issues," was the conclusion of a major study on the future of coal by the Massachusetts Institute of Technology in 2007. The big issues are time and cost: even proponents of CCS don't expect the process to be commercially viable until 2020.

What are the cost considerations?
Capturing carbon emissions is a process that itself requires energy: indeed, a quarter of the energy produced by CCS plants - first generation ones, at any rate - will be used up in the process of scrubbing, compression and transport. So they'll be a lot less efficient than existing coal-fired stations, and their electricity that much more expensive. Besides, only a handful of old power stations in Europe and the US can be retrofitted with the new technology (there's greater potential with China's more modern fleet) and for those that can be, the bill will be huge. In short, it will cost billions to research, test, build and run CCS facilities - which is why both government and the private sector seemed, until recently, to be cooling on the whole idea. Last year, the Bush administration withdrew funding for the first US clean coal power station after costs rose to $1.8bn.

So why has 'clean coal' become hot again?
The politics of the recession. Several governments have put CCS at the centre of their plans to restart their economies via investment in green technologies. The EU has pledged €1bn to help get 12 demonstration plants up and running, while the Obama administration has resumed funding for FutureGen, America's clean coal initiative - the largest in the world. The G8 wants 20 CCS demo plants launched worldwide by next year.

And what's happening in the UK?
Britain embraced clean coal in April when the Government announced it would build four new CCS power stations, starting with the Kingsnorth plant in Kent, and that all new coal-fired power stations built in the UK would have to be fitted with the technology. At first, the equipment will only have to cover 25 per cent of emissions produced, but that will rise to 100 per cent around 2020. The CO2 will be stored in empty oil and gas fields under the North Sea. Last month, the Government said it would help pay for the new plants by levying a new tax on electricity by 2011.

So is it full-steam ahead then?
Yes, though it won't be a smooth ride, not just for technical and financial reasons, but for political ones, too. In Germany, where CCS testing has been going on far longer than in the UK, a new law mapping out how the country will adopt the technology has been delayed because of widespread opposition, with local communities expressing fears about CO2 leakage from potential storage sites. In the UK, similar tensions are surfacing, as business groups press the Government to build more nuclear and CCS plants, while the green lobby worries that the hunt for clean coal will crowd out investment in truly renewable sources of energy, such as wind power. But as proponents of CCS see it, there is no choice but to invest in clean coal since whatever happens in the West, India and China are going to press ahead with building coal-fired power stations whether the technology is there or not. China, the world's largest polluter, is building one new coal-fired power station each week. So better ensure that the coal is clean.  ·