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Energy»Could Clean Coal Answer our Problems?

»Friday, March 19,2010

Billions of tons of Coal buried too deep to mine using traditional methods  can now be harnessed, providing potentially clean energy.Coal has become the ugly sister of power sources, condemned as old-fashioned, ultra-polluting and excessively costly to mine, given that we have exhausted the most easily accessible supplies.


Yet beneath the Firth of Forth, in a coalfield of more than 200 square miles, a project is taking shape that, if successful, would offer an affordable means of reaching billions of tons of deep-lying coal deposits without causing irreparable harm to the environment.

The Firth of Forth field is so deep – 500 metres or more beneath the surface – that it has not been cost-effective to mine. The attraction of exploiting it has further diminished because of the link between global warming and fossil fuels.

The new scheme, however, would couple two recently improved technologies – underground coal gasification and fuel cells. Rather than having the coal dug out, oxygen and water would be pumped down the mine to create a white-hot chemical reaction that turned the coal into gas. This process would not only generate electricity more efficiently than wind, nuclear or conventional gas and coal power plants, but would enable the capture and storage of more than 99 per cent of the CO2 contained in the fuel before it escaped into the atmosphere.

The construction of such a carbon capture and storage (CCS) facility means that environmental objections to using coal as a fuel would be dramatically diluted. Equally, it would enable much more of the world's remaining coal deposits to be mined – in Britain alone there are an estimated 17 billion tons suitable for the CCS process.

Coal has been a driving force of the world economy since the Industrial Revolution, and with China, India and the United States sitting on huge reserves, it is expected to remain so for decades, or even centuries, to come. China and the US, the world's two biggest greenhouse gas producers, both rely heavily on coal – China, which burnt 2.74 billion tons in 2008, obtains 80 per cent of its electricity from coal, while the US derives 65 per cent.

Annual world consumption of coal is more than 6.5 billion tons, which by 2030 is forecast to rise to 10 billion tons. Scientists have repeatedly given warning that if emissions from fossil fuels continue to rise, there will be little hope of avoiding catastrophic levels of climate change – unless the carbon dioxide can be captured and stored.

At the Firth of Forth field, this could be done quite simply. First, the gas produced from the so-called "flash-frying" of the coal would be piped to the surface and cleaned of contaminants. Then it could be run through a traditional generator. But there is a more effective alternative, which involves the gas being separated into two streams. One would consist of hydrogen, which could be fed into high-efficiency fuel cells to be turned into electricity; the other would be the carbon dioxide, for storage. The key to the process is low-cost, alkaline fuel cells, developed by AFC Energy Ltd, which turn hydrogen into electricity, with water as a by-product.

Such is the potential of the scheme that despite its use of coal, usually a guarantee of the environmentalists' ire, it has won the approval of Friends of the Earth. Neil Crumpton, the FoE's energy specialist, describes it as an opportunity to "demonstrate carbon capture technologies without the excuse of claiming to need to build a massive, new coal power station".

With a deal having been struck between Thornton New Energy, which has the licence for the gasification, and Waste2Tricity, which holds the rights to the fuel cells, the scheme is expected to be providing electricity for 25,000 homes by 2012.

"If it all works as planned, it will be a phenomenal step forward," says Ian Arbon, Waste2Tricity's newly appointed chairman and a professor of alternative energy at Newcastle University. "It's the first really sustainable way of developing power from coal that I've come across. It's one of the most exciting things I've ever seen."





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