Reducing Greenhouse Gas Emissions

Fugitive emissions from coal seams are one of the main sources of greenhouse gas emissions in the NSW coal industry.  A large component of fugitive emissions is the gas methane, a potent greenhouse gas but also a useful source of energy otherwise known as natural gas.  Fugitive emissions occur at both underground and open cut mines with actual emission levels varying based on local geology and the depth of soil and rock over the coal seam.

Historically, fugitive emissions from underground coal mines were directly released into the atmosphere to ensure underground mining could be done safely.  But over the past 10-15 years, some mines have been able to begin capturing the methane and either flaring it, which reduces its greenhouse impacts, or using it for electricity generation.  Any electricity generated can be used to power on-site operations or fed into the grid, both reducing demand for other types of electricity generation.  For example, Illawarra Coal has installed 94 x one megawatt gas turbines which generate enough power for approximately 60,000 homes, using methane drained from coal seams.  This project was a world-leader in 1996 and was the largest coal mine methane project in the world until a bigger Chinese project was commissioned in 2008.  The Illawarra Coal project is estimated to reduce greenhouse gas emissions by over 3 million tonnes CO2-equivalent per year.

The capture and combustion of fugitive emissions is only viable under certain circumstances.  Some of the factors that affect viability include the concentration of methane in the coal seam and the ability to generate a continuous gas stream.  It is virtually impossible to capture fugitive emissions from open cut coal mining as the gases slowly release through the earth’s surface over time.

The use of diesel fuel is another source of direct greenhouse gas emissions from mining operations.  A number of mines in NSW have investigated the use of alternative fuels, such as renewable biodiesel, to reduce the volume of conventional diesel consumed on site.  This can significantly reduce the greenhouse gas emissions from diesel fuel use.

Energy efficiency measures are discussed further in the next section.

Relevant Documents

Fact Sheet – Energy and Greenhouse in the NSW Minerals Industry

Case Study – BHP Billiton Illawarra Coal: Appin Tower Power Project

Case Study – United Collieries Flaring Project