The site

For almost two decades Illawarra Coal has been capturing and utilising the methane gas which, for safety reasons, is drained from coal seams prior to mining. The gas has been piped to gas engine power plants near the townships of Appin and Douglas Park since 1995, reducing the company’s annual greenhouse gas emissions by 2.5 million tonnes and producing enough energy to power around 60,000 homes each year.

However, not all the methane associated with the coal seam is able to be drained and small percentages of methane are present in ventilation air exhausted from the underground operations. To address this, BHP Billiton Illawarra Coal, in partnership with international emission control specialist MEGTEC Systems AB, established a pilot plant at its Appin site to trial the use of VOCSIDIZER© technology to use methane in the ventilation air for electricity generation. The success of this pilot led to the establishment of WestVAMP, which has a wide potential application for global methane abatement and power generation.

A new type of power plant, WestVAMP uses the extremely dilute methane in the ventilation air from West Cliff mine to generate electricity. It will use up to 20 per cent of the mine ventilation air to achieve a further reduction in greenhouse gas emissions of 250,000 tonnes of carbon dioxide equivalent (CO2-e) every year.

Technology

The VOCSIDIZER© technology works by merging two conventional technologies - emission control technology and a steam cycle power plant. The boiler process is based on flameless, single bed, regenerative oxidation in a unit called the VOCSIDIZER©.

WestVAMP converts low concentration methane to carbon dioxide and water vapour through an oxidation, or flameless combustion process. High efficiency heat exchangers recover the large levels of thermal energy released to produce high quality steam. This steam is used to drive a conventional steam turbine – generating six megawatts of electricity for use within the West Cliff mine.

Energy purchase and supply

The plant generates baseload power which is used by West Cliff Colliery. The generator is an accredited generator under the NSW Greenhouse Abatement Scheme. It is expected that the plant will produce 35 gigawatt hours (GWh) of electricity per annum. The generator is exempt from registration as a generator in the NEM as it is too small. The plant is connected to the West Cliff Colliery 11 kilovolt (kV) busbar. The Colliery is connected to the Integral Energy Sub-Transmission Network at 66 kV and the Colliery’s ventilation system supplies fuel for the plant.

Environmental Impact

The project is expected to save 250,000 tonnes per annum of greenhouse gas emissions. The thermal efficiency of the oxidation process is over 90 per cent. The steam turbine efficiency is less than 30 per cent.

Success of the project to date

The project has abated in excess of 100,000 tonnes CO2-e and generated over 10 GWh of electricity since commissioning.

Funding arrangements and acknowledgements

AGO funding under GGAP Round 2 of $6 million.

Quote

“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 AB.” NSW Premier Morris Iemma