Electricity Generation

Introduction

This content is currently under review. Statistics date from 1990.

Electricity generation in Australia is dominated by large thermal power stations. In Queensland, New South Wales and Western Australia, black coal is the main fuel; in South Australia, it is sub-bituminous black coal and natural gas; and in Victoria it is brown coal. The installed capacity of hydro-electricity generating stations is 7,500.7 MW, which is 19.4 per cent of the 1997 total installed capacity of 38,698.3 MW (ESAA 1998). In terms of electricity generated, hydro-stations produced 16,805.6 million kWh, 10.0 per cent of the 168,871.4 million kWh total electricity generated in 1996-97. This reflects the generally lower operating capacity of most hydro stations and their particular contributions to peak power supplies. At the state level, however, hydro power is dominant in Tasmania.

Electricity generation in the Murray-Darling Basin

Most of the electricity consumed in the MDB is generated in the large thermal power stations that are located outside the Basin. However, the Basin occupies a unique place in Australian electricity generation in that it is the location of over three-quarters of the mainland's hydro-electric power (hep) stations. The Snowy Mountains hydro-electric scheme is the largest scheme and includes the largest individual power stations (SMA 1997). However, there are numerous other hep stations in the New South Wales and Victorian parts of the Basin. These are listed in Table 1 and their locations shown in Figure 1.

Figure 1: Electricity Generating stations in the MDB

The Snowy Mountains scheme was built to generate electricity and to supply water for irrigation in the Murray and Murrumbidgee valleys. In Victoria, the Rubicon and Kiewa Valley schemes were built specifically to generate electricity. At all other locations, with the exception of Mannus Creek near Tumbarumba, hep is a secondary function to the storage of water for irrigation and other purposes.

As Table 2 indicates, there are a number of sites within the MDB that have the potential for hep generation (Paterson 1985). Some of these have been or are in the process of being developed, all of them by private companies. These companies operate under licence to the respective dam owners, with fees based on the services provided and the electricity generated. Most of the developments are relatively small stations at existing reservoirs. In addition, the capacities of some existing stations could be expanded. A number of other sites have been removed from consideration for environmental reasons, including the creation of national parks. No account is taken in this chapter of sites for mini hydro-power schemes, such as exists at Yarrangobilly Caves in the Snowy Mountains.

In the western parts of the Basin, gas turbine and diesel generating plants supply electricity to isolated communities that are not linked to the main distribution grid system (Table 3). Others provide emergency stand-by equipment at places distant from the main generating facilities, such as Cunnamulla. A solar station operates at White Cliffs, while at Crookwell, a 4.8 MW wind farm has recently been brought into operation.

There is only one major thermal generating stations currently within the Basin, namely Mount Piper (1,320 MW); located east of Bathurst, it is only just in the Basin. However, this is a situation that could change significantly. At Oaklands, south west of Albury, Mitsubishi and CRA have investigated the construction of a 2,800 MW power station to supply both New South Wales and Victoria. The Rylstone area has also been considered as a potential site for a 2,640 MW thermal power station. In the Gunnedah area, there are sufficient coal supplies to support up to four 2,640 MW power stations, but this would only be possible with the transfer of water from the Apsley River, a tributary of the east-flowing Macleay River, to the Namoi for cooling purposes. The similar development of coal resources in Queensland's Condamine Valley would also require the inter-basin transfer of water for cooling purposes.

Hydro-electricity in the MDB

Hydro-electricity generation in the Murray-Darling Basin is dominated by the Snowy Mountains scheme. However, as has been indicated, there are many other hep stations, some established specifically as such, though most of them are attached to water storages built primarily in the interests of irrigation. Almost all of the recently constructed stations are owned and operated by private companies.

The Snowy Mountains Scheme

The Snowy Mountains scheme occupies a very special place in Australia's history (Wigmore 1968; Gare 1992; SMA 1997). Though it straddles the border of the Murray-Darling Basin, it is intimately linked with the Basin. Extending over an area of 7,000 km², it was completed in 1974 after a twenty five year construction period. It involves 16 major dams and numerous smaller diversion structures, some 150 km of tunnels, 80 km of aqueducts, a major pumping station, and seven hep stations with a total capacity of 3,756 MW (Figure 2).

Figure 2: The Snowy Mountains hydro-electric scheme

With an installed capacity of 1,500 MW, Tumut 3 is the largest hep station in Australia and also operates as a pumped-storage scheme. In 1996-97, 5,010 million kWh were generated for supply to the ACT, New South Wales and Victoria. In terms of mainland Australia, the Snowy Mountains Scheme accounts for 71.7 per cent of installed hydro capacity and 69.5 per cent electricity generated in hydro stations. An on-going $400 million rehabilitation scheme is particularly concerned with the refurbishment of the generating stations.

The Rubicon scheme

The Rubicon scheme is a purely hydro-electric development consisting of four small hep stations that make use of the natural flows of the Rubicon and Royston Rivers, tributaries of the Goulburn River, located near Victoria's Eildon Reservoir (SECV 1982; Evans 1994, 83-108). It is a small scheme, with a total capacity of 13 MW. Its output is highest in winter and spring. The scheme now makes only a very small contribution to total electricity supplies, but when completed in 1928, it accounted for one-fifth of the then Victorian State Electricity Commission's supplies.

Wyangala Dam

Almost all of the individual hep stations in the MDB are located at reservoirs built to store water for irrigation and other purposes. This means that electricity generation is a secondary function of the reservoirs and is dependent on water releases from them.

The 20 MW hep station at Wyangala Dam, on the Lachlan River near Cowra, was completed in 1992 by Hydro Power, a private company consisting mainly of local farmers. It is a fully automatic facility, located just below the Dam, and makes use of water released for irrigation purposes in the Lachlan Valley. All of the electricity generated is sold to the regional electricity distribution company, which operates the remotely controlled power station from its offices in Young. The power station is providing savings to the regional distribution distribution company, Advance Energy, and revenue to the NSW Department of Land and Water Conservation for use of the water to generate the electricity.

It is of interest to note that a 7.5 MW hep station operated at Wyangala from 1949 until the enlargement of the Dam in the late 1960s.

Yarrawonga Weir

The 9.6 MW hep station at Yarrawonga Weir was completed in 1995 at a cost of $16 million by a private company, Power Facilities Ltd. It uses water released from Lake Mulwala and can produce enough electricity to supply a town the size of Benalla. It is unusual in that it operates on a very low head of water, down to 3 metres.

Conclusion

The presence of the Snowy Mountains scheme means that the Murray-Darling Basin is an important part of electricity generation in Australia. The scheme provided the first interconnection between the New South Wales and Victorian electricity grid systems. It now forms part of a grid linking the four mainland eastern states, much of which is located in the Basin, facilitating the development of a common electricity market. With the construction of a number of small hydro schemes and plans for others, hydro-electricity generation will increase in importance in the MDB, especially at the local and regional levels. If one or more of the possible large thermal stations is constructed, then the Basin's importance as a source of electricity will increase substantially.

References

ESAA (1998): Electricity Australia 1998. Electricity Supply Association of Australia, Sydney.

Evans, P. (1994): Rails to Rubicon: a history of the Rubicon Forest. Light Railway Research Society of Australia Inc., Melbourne.

Gare, N.C. (1992): "The Snowy Mountains Scheme". Revue de Géographie Alpine, 80(2-3), 201-225.

Paterson, R.H. (1985): A Survey of Small Hydro Potential of Large Dams Operating in Australia. National Energy Research Development and Demonstration Program Report No. 619. Department of Resources and Energy, Canberra.

SECV (1982): Victoria's Hydro Power. State Electricity Commission of Victoria, Melbourne.

SMA (1997): The Power of Water: the story of the Snowy Scheme. Snowy Mountains Hydro-Electric Authority, Cooma.

Wigmore, L. (1968): Struggle for the Snowy: the background to the Snowy Mountains Scheme. Oxford University Press, Melbourne.

Annual reports and other publications of the various state and private electricity generating organisations.

Table 1 Hydro-electric stations in the Murray-Darling Basin  (source: various reports, including those of the state and private electricity organisations)

Table 2 Future development of hep in the Murray-Darling Basin

 (a) Planned/proposed hydro-electric power stations 

(b) Potential sites

Table 3 Thermal and other power stations  (source: various reports, including those of the state and private electricity organisations)