Sunday, May 06, 2007

"Clean Coal" ?

As governments, mining companies and political parties scramble to gain their green credentials with the (voting) public, it is worthwhile us looking at what they offer.

"Clean coal" has been bandied around as a saviour: a means where we can continue to mine, export and use coal at existing or higher rates, but not pollute the atmosphere with more carbon dioxide. The trouble with carbon dioxide is that it reduces the earth's ability to cool itself by radiating heat into space, mostly at night. So, the earth collects heat from the sun, becomes hotter, but can't cool itself as well. This leads to increasing average temperatures across the earth = "global warming" and all the associated weather, ecological and environmental effects.

Coal is substantially carbon. Depending on its colour and sheen, it has varying amounts of sulphur, water, hydrogen and substantially-decomposed plant material, from which it is derived.

"Clean coal" technologies promoted by the Australian Coal Association ( include technologies to:
  • reduce fly ash escaping from chimney stacks
  • using pulverised coal dust in furnaces (like having fuel injection for cars)
  • converting coal to gas (a process that uses more energy than the energy in the the gas it makes)
  • other methods to improve the efficiency of combustion
All of these are admirable (except for converting coal to gas, which is energy-inefficient). Add to the mix the "new technology" of carbon sequestration. Say what?? Essentially burying carbon dioxide pollution underground, so that it doesn't contribute to global warming.

There is one inevitable truth about this that its proponents do not tell you:
  • for every 100 million tonnes of carbon dioxide buried, they also bury almost 73 million tonnes of oxygen - oxygen that we, and every other living thing needs to survive!
Clean coal?? By all means develop more efficient methods of combustion (so we burn less), and reduce the sooty and other particle emissions from smokestacks.

But please don't bury the very oxygen we need to survive! "Clean coal" is NOT the environmental cure that many politicians are saying.

The Analyst