Power from waste

Electricity from a power plant which is run on waste gas from a Hunter Valley coal mine will soon supplement the local grid as Energy Australia has agreed to buy the electricity generated from a new power plant.

Construction began on the Glennies Creek waste gas power plant in November 2006 and it is anticipated that it will begin operating as early as August this year.

Australian company Envirogen will operate the $80 million plant, which will convert the waste gas from the nearby Glennies Creek Colliery into electricity for Energy Australia.

The company is already running three similar power stations: at Tahmoor colliery south of Sydney, Teralba Colliery near Toronto in NSW and Oaky Creek in Queensland's Bowen Basin.

CEO at Envirogen, Jeff Rice told Waste Streams that the 10-megawatt power plant will produce enough electricity to power 10,000 homes. "This will deliver approximately 208,000 tonnes of carbon abatement each year," he says.

Rice explains how the technology works. "The mine vents waste mine gas, which is high in methane content, to the atmosphere as part of the core mining drainage of the underground coal to be mined. This is to reduce the gas content in the coal block to acceptable levels for mining.

"This is achieved by drilling multiple holes in the coal block underground and linking these to a vertical drilled hole that leads to the surface where the gas is vented to the atmosphere.

"Envirogen connects a poly gas pipeline to link these surface wellheads to the power station and the gas is pumped to the power station by suction blowers located at the power station.

"The methane is then combusted in individual 1 MW gas reciprocating engines which are directly linked to generators which, following a step-up in voltage, deliver the power into the main high-voltage grid.

Rice says that the high-methane waste gas is 21 more times damaging to the environment than carbon dioxide, which is produced and emitted after the gas is combusted.

"At the station, the gas is drained of excess water and filtered to a very fine tolerance before it is compressed and cooled. It is then fed to the containerised 1 MW generating units."

The electricity produced at the plant will be available for general consumption as it is being fed directly into Energy Australia's grid. The Iemma government says that the environment benefits as the resultant electricity offsets the electricity that would otherwise need to be generated from large coal-burning power stations.