AUSTRALIA: Cleaner energy from coal

Clean, cheap, greenhouse friendly energy obtained by burning coal while it's still underground could be a major power source for Australia in the new millennium, says the Commonwealth Scientific and Industrial Research Organisation (CSIRO).

Industry and government in Australia are now showing strong interest in rejuvenating an old, but little known technology referred to as Underground Coal Gasification (UCG), say Dr Cliff Mallett of CSIRO Exploration and Mining.

“UCG holds many environmental advantages over conventional mining and combustion of coal for energy,” says Dr Mallett. “The greatest benefits are the production of a clean, environment-friendly gas for power generation without the pollutants normally associated with coal-fired power plants”

UCG cuts greenhouse gas emissions from coal by combining the extraction of the coal with its conversion into energy.

“With increased control over the processes driving UCG it is possible we could reduce emissions of carbon dioxide by almost half of that released from conventional coal fired power stations,” says Dr Mallett.

Other pollutants such as coal ash, some chars, tar, sulphur in the form of hydrogen sulphide and nitrous oxide are either left in the ground or easily removed from the product gas via a cheap and efficient existing technology.

“Energy from UCG should also be cheaper as it replaces the immense capital costs associated with the mining process. It is also a huge step forward for human safety, as no workers are needed underground,” says Dr Mallett.

The technology has already been tested in the United States of America, China and Europe. Their research has focussed largely on extracting more energy from the conversion of coal into gas.

CSIRO wants to direct its research towards development of new UCG processes and work out how to control the chemical reactions occurring underground to produce a higher quality, greenhouse friendly gas. “At the same time we hope this will mean less pollutants released into the atmosphere,” says Dr Mallett. He concedes this will mean sacrificing some of the potential energy that could be converted from the coal.

“The capacity for this technology to supply Australia with a cleaner form of energy is enormous,” says Dr Mallett. “The amount of coal suitable for use in UCG is much greater than the reserves available to conventional mining, as it utilises coal that is otherwise unrecoverable or unusable.”

First suggested by the British over 100 years ago, UCG was eventually exploited by the Russians in the 1930s. Major advances in UCG failed to occur, however, until the 1970s when the United States of America realised the need for a concerted research effort into this languishing energy potential.

The UCG process converts coal to a gaseous mixture of hydrogen, methane, carbon monoxide and carbon dioxide. Air and steam are injected into the coal seam and used to initiate and maintain coal combustion. The resultant combustible and other gases are piped to the surface directly to power generation or industry facilities.

Environmental risks do exist with UCG. Dr Mallett emphasises that the risks can be avoided through correct site selection. “It is critical you find the right spot. The wrong location can mean reduced quality and quantity of the product gas as well as environmental problems such as groundwater contamination.”

The CSIRO is holding a workshop on Underground Coal Gasification to bring together industry, government and associated experts to discuss the potential of this technology for Australia and the world.

The workshop will be held on March 23 at the CSIRO Queensland Centre for Advanced Technologies.

For more information Contact:

Dr Cliff Mallett CSIRO Exploration and Mining, ph. (07) 3212 4440

Judith Thomson CSIRO Exploration and Mining, ph. (08) 9333 6397

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