Methane gas generates electricity

Mining Chronicle
May, 2008 Page: 64

While looking at ways to reduce its water consumption, Illawarra Coal was also working on its world-first WestVAMP power plant at West Cliff Mine and developing energy savings actions plans for its operations. The company's operations consumed 307 gigawatt hours of electricity and 2011 kilolitres of distillate to produce 6.89 million tonnes of clean coal in 2006-07. It recognised that there was more work to be done to reduce usage.

While methane, drained from underground mine workings, has been used to generate electricity at the Appin and Appin West methane gas engine power plants for almost two decades, generating up to 440,000 megawatt hours of electricity a year, the company saw another window of opportunity - using the methane gas from mine ventilation air to generate electricity.

It chose to trial Vocsidizer technology pioneered by Swedish emission control specialist MEGETC Systems, which works by merging two conventional technologies - emission control technology and a steam-cycle power plant. The resulting operation - which represented a spend of about $30 million including a $6 million Australian Greenhouse Office Greenhouse Gas Abatement Program contribution - was officially opened by NSW Premier Morris Iemma on September 14 last year.

Mr Iemma said it was a "great day" for the region, the state and the nation. "This facility will make a significant contribution to greenhouse gas reduction in NSW and I applaud the ingenuity of Illawarra Coal and its technology providers MEGTEC Systems," he said. Illawarra Coal president Colin Bloomfield said the project was a fine example of BHP Billiton's Climate Change Policy in action.

"The policy is about delivering real reductions in the greenhouse gas intensity of our production processes and WestVAMP is making a significant contribution to reducing BHP Billiton's carbon footprint," he told the opening. "The support of the Australian Greenhouse Office Greenhouse Gas Abatement Program with a $6 million contribution was also critical to the commercial viability of the investment." By the end of last year, WestVAMP had reduced the amount of electricity consumed by West Cliff Mine by about 35,000 megawatt hours per year.

The plant uses up to 20 per cent of the extremely dilute methane in the ventilation air from the mine to generate electricity. It is expected to achieve a reduction in greenhouse gas emissions of 250,000 tonnes of carbon dioxide equivalent every year - the equivalent of eliminating emissions from 45,000 cars annually or producing enough electricity for 20,000 homes. In its first six months of operation alone, WestVAMP abated more than 88.000 tonnes of carbon dioxide equivalent and exported about 10,000 megawatt hours of electricity to the West Cliff Mine.

The operation was almost immediately named the winner of the Australian Institute of Energy Award. Handed out just once every two years, the prize recognises and rewards individuals and organisations who have made an outstanding contribution to the energy sector in NSW and/or the ACT. Illawarra Coal's award in the Energy and Environment category acknowledged WestVAMP's contribution to improving environmental performance in the energy industry.

Together with its previous methane capture initiatives, WestVAMP makes Illawarra Coal one of the largest single contributors to greenhouse gas emission reduction in NSW. But saving (and creating) electricity and water weren't the only environmental issues on the company's mind last year. Noise and dust were its major considerations during the construction of a new coal sizer at Dendrobium Mine.

Approved by the Department of Planning early in 2006 following extensive consultation and a number of changes aimed at reducing impacts on the community, the sizer was completed last March. Its aim is to allow the mine to reduce the size of large slabs of material to a safer and more manageable size for transport and handling.

During the seven-month construction phase, the mine kept the local community informed of progress through meeting residents living close to the site, newsletters, information sheets delivered to homes and briefings to the community consultative committee including a site tour once construction was complete. Noise studies on completion confirmed noise levels were well within those specified in the consent applications.