BROWN COAL AND COAL COMBUSTION

Brown coal, also known as lignite, is mined at the Hazelwood mine. Brown coal is a soft, dark brown sedimentary rock that forms naturally in the ground. Unlike other types of coal, brown coal has high moisture content and is made up of highly volatile matter. This makes it easy to burn as a fuel for power generation, but also makes it susceptible to spontaneous combustion.1

Where brown coal is found in thick seams near the earth’s surface (as is the case at the Hazelwood mine), it can be mined on a large scale using open-cut methods. The Latrobe Valley has large deposits of brown coal and the Hazelwood Power Station generates approximately 25 per cent of Victoria’s electricity.2

In order to generate electricity, brown coal is first pulverised and then burnedin large-scale boilers. The heat from the burning coal boils water, and the steam produced is then used to drive turbines that create electricity.3

COAL COMBUSTION DURING THE HAZELWOOD MINE FIRE

When coal combusts it produces smoke and ash. During the Hazelwood mine fire, coal burned outside the industrial machinery made to house burning coal, and without any type of processing. This uncontrolled and open setting meant that coal burned at varying temperatures, and emitted smoke and ash that were different to that produced by the power station stacks.4 In his evidence to the Board, independent expert Professor Donald Campbell, Professor of Medicine, Southern Clinical School, Monash University and Program Director, General Medicine Program, Monash Health, advised that the smoke produced from a coal fire is different to that of a bushfire. In brown coal fires, the carbon monoxide levels are higher and polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds (VOCs) are a concern.5