Coal bed methane project aims to reduce emissions

Designing for the future to reduce our greenhouse gas emissions and become part of the solution to climate change is one of the elements of Rio Tinto Coal Australia's climate change action plan.

In 2007 Rio Tinto Coal Australia started a world-first project to capture and process methane gas from its open cut Mount Thorley Mine in the Hunter Valley.

Methane gas, associated with the exposure of coal during the mining process, is among the dominant contributors to Coal & Allied's emissions profile followed by electricity and diesel.

It has a global warming potential 21 times that of carbon dioxide, which means releasing one tonne of methane into the atmosphere is like releasing 21 tonnes of carbon dioxide.

Rio Tinto Coal Australia's $5.5 million coal bed methane project, divided into two stages, was designed to reduce methane emissions.

Following a data collection stage, we are now proceeding to a four well pilot flare programme to progress this work in 2008.

The methane released from these wells will initially be flared as part of the measuring process.

However, if the project yields a significant amount of methane, Rio Tinto Coal Australia may look at using it to generate electricity.

"The coal bed methane project provides an opportunity to minimise our greenhouse gas emissions by reducing methane emissions to the atmosphere from mined coal seams," Rio Tinto Coal Australia Managing Director Hubie van Dalsen said.

Mr van Dalsen said about 63 per cent of greenhouse gas emissions at Rio Tinto Coal Australia sites (four in Queensland, and three in NSW) came from methane emissions.

"We are already targeting the remaining 37 percent of emissions sources through mitigation
projects, so this coal bed methane project is now an excellent opportunity to make a positive step change to reduce our overall greenhouse gas emissions," Mr van Dalsen said.

"Mount Thorley Warkworth currently emits about one million tonnes of carbon dioxide
equivalents each year, and this project is estimated to reduce that amount by up to 400,000 tonnes per year, or 40 per cent."

If the pilot project is successful, it could trigger similar developments at the other Hunter
Valley sites, and perhaps also in Queensland.

The overall success of the trial will depend on the company being able to extract the gas in a commercially viable way.

This will depend on issues such as the cost of extraction, the quantity of gas extracted before
mining reaches extraction wells, and the potential liability of the greenhouse gas remaining in seams when mined.