Department of the Environment

About us | Contact us | Publications

Settlements Header ImageSettlements Header ImageSettlements Header Image

Environment industries archive


Key departmental publications, e.g. annual reports, budget papers and program guidelines are available in our online archive.

Much of the material listed on these archived web pages has been superseded, or served a particular purpose at a particular time. It may contain references to activities or policies that have no current application. Many archived documents may link to web pages that have moved or no longer exist, or may refer to other documents that are no longer available.

Eraring Power Station
Cleaner Production - Effluent Reuse in Power Generation - Eraring Energy


Eraring Power Station (Eraring), is a 4 x 660 megawatt coal-fired power station and provides some twenty-five per cent of NSW power requirements. Eraring is located in close proximity to Dora Creek sewage treatment plant (STP), north of Sydney.

The cleaner production initiative at Eraring was recognised by a Highly Commended classification in the inaugural NSW EPA, ACCP and AWWA 1996 National Cleaner Production Award.

Eraring Power Station became part of Eraring Energy in August 2000.

Pre-excisting Process

Process flow chart

Eraring uses recirculated water from Lake Macquarie for the cooling of the plant. Prior to 1991, approximately 8.5 million litres of fresh water was used daily, predominantly for boiler feed water, cooling purposes and washdown

A site water audit identified various plant modifications that could reduce water consumption. Implementing the audit's recommendations has meant that daily fresh water requirements have dropped by approximately 50% to around 4 million litres.

Cleaner Production Initiatives

Concurrently with water conservation initiatives at Eraring, Hunter Water Corporation (HWC) established a project to pump treated effluent from the nearby Dora Creek STP to an ocean outfall in the Pacific Ocean. The outfall was planned to pass close by Eraring Power Station. An opportunity was identified by Eraring to utilise the treated effluent as a potential source of water.

Investigations carried out by Eraring indicated that a combined membrane filtration and reverse osmosis system designed to remove suspended solids, bacteria, viruses and dissolved salts, would enable the effluent to be used at Eraring. Eraring Energy believe that this is the world's first example of effluent from a STP being used to supply feedwater to high pressure boilers.

Eraring Water Reclamation Plant

HWC and Eraring signed a fifteen year agreement that would enable daily access to 5.2 million litres of effluent at 20C. Membrane filtration, which is an almost chemical-free method for the removal of solids and bacteria from the effluent, could be set up in modular units to meet the power station's supply demands.

As the only disposal method for effluent from the Dora Creek STP was to be use at the power station, a series of security features formed an integral part of the design. A large storage dam at the Dora Creek STP combined with dual membrane filtration and reverse osmosis units with standby pumps and crossover facilities, provided a 50 percent over capacity for dry weather flows. Large storage water tanks were included as insurance against plant failure.

Advantages of the Process

Use of the effluent by Eraring has enabled significant savings in town water and operating costs by the deferment, for at least fifteen years, of any need for the ocean discharge of effluent from the Dora Creek STP.

Beneficiary Costs Savings achieved
Eraring Energy (formerly part of Pacific Power) $4.2 million  (initial -see below for further costs) $0.9 million pa in water costs (at full operating capacity)
$100,000 pa in operating costs
Hunter Water Corporation   $2.5 million due to pipeline deferment

A cost-benefit analysis based upon an initial capital cost of $4.2 million and assuming a worst-case membrane replacement scenario, yielded an eight year payback period (Note that a longer payback than suggested by the figures in the table resulted because the full savings from reduced water usage were not achieved immediately). This was acceptable to Eraring Energy for the power station which has an expected remaining life of approximately thirty years.

Cleaner Production Incentive

Eraring management was motivated to look for innovative solutions to achieve cost reductions. The effluent use option complemented the organisation's program to minimise its daily water requirement at Eraring. The combination of economic viability, water conservation and minimal environmental impact were compelling reasons.


The use of STP effluent for boiler feed water posed an area of concern for the company, whose supply conditions to the state power grid demanded that the reclamation strategy not interfere with the provision of uninterrupted electricity supply. The company therefore had to be certain that there would be no adverse operational consequences from using STP effluent.

Further Developments

Eraring Energy has continued to benefit from this project.

In June 2000 extra membrane filtration was installed at a cost of over $0.5 million. This initiative was designed to allow operation at full capacity whatever the weather and achieve savings of a further $0.3million pa in water costs.

Membrane filters

Membrane filters


David Williams
General Manager/Production
Eraring Energy
Eraring Power Station
PO Box 5044
Ph:  61 2 4973 0521
Fax: 61 2 4973 0716
Date of implementation: Commissioned March 1995.
Date of further initiatives: June 2000.
Case study prepared: May 1997 by ACCP.
Date last modified: May 2001.
ACCP logo