The methane and waste coal burning turbine system will dramatically reduce both fugitive gas emissions from underground coal mines and the gases resulting from spontaneous combustion of waste coal, CSIRO said.

Coal mine emissions make up an estimated 6.7% of Australia's total greenhouse emissions with environmentally toxic methane gas emissions from underground coal mines contributing 5.7% of this.

Gases emitted from the industry's waste coal - on average 800,000 tonnes per mine each year - contributes a further unknown amount of greenhouse gases.

Fuelled by a variable mix of methane and waste coal, CSIRO said the turbine furnace system would substantially reduce these emissions while offering big savings and improved waste management.

"Waste coal accounts for 8% of a coal mine's budget and also contributes to the proliferation of environmentally unfriendly dams and spoil piles," Patrick Glynn, CSIRO project leader, said.

"By recycling it, this technology has the potential to save millions of dollars annually."

Electricity from the system can be used to power the mine or be fed back into the grid, which CSIRO said would displace hundreds of megawatts of electricity currently produced by fuels that produce seven times more greenhouse gases than burning methane.

'The system's development has been funded by CSIRO, the Australian Coal Association Research Program (ACARP), the NSW Sustainable Energy Development Authority (SEDA) and Brisbane-based Liquatech Turbine Co, which will commercialise the technology.

A 1.2MW plant has already been successfully demonstrated in Queensland and a mine-scale demonstration plant is planned for NSW in 2003.

The plant burns the coal and methane (either from gas drainage or mine ventilation air) in a kiln producing hot air which passes through a heat exchanger to drive the gas turbine.

"The system is significantly cheaper and more efficient than steam-powered systems because it does not require water treatment systems, condensers, cooling towers or high-pressure fluid handling systems," Glynn said.

Suitable for small-scale plants in remote locations, this "dry" system is almost as efficient as modern combined-cycle power plants.

"Ash from the kiln can be used to produce lightweight expanded aggregate for use in marketable products such as lightweight concrete and concrete blocks, clay brick filler material and insulation material," Glynn said. "Mines will be able to sell the aggregate or use it in day-to-day mine maintenance."

In addition waste heat from the process can also be used to dry tailings which can be burnt or added to the exported product.

Mines using the technology may be entitled to carbon credits for reducing environmental damage.