Hydroelectricity

Hydroelectricity – how it works

Hydroelectricity, also known as ‘hydro’, is a well-developed renewable technology that has been around for more than a century. It uses the energy of flowing water to spin a turbine connected to a generator that produces electricity. The amount of electricity generated depends on the volume of water and the height of the water above the turbine.

Hydroelectricity does not actually ‘use’ water: all the water is returned to the river.

Large hydroelectric power stations need dams to store the water needed to produce the electricity. These dams are often built for irrigation or drinking water, and the power station is included in the project to ensure maximum value is extracted from the water. Hydro can provide both base load and peak load electricity; and hydro generators can start up and supply maximum power within 90 seconds. Smaller hydro power stations, called mini or micro may not need dams but rely on naturally flowing water such as streams. These also provide a good source of power and are often used as stand-alone systems not connected to the main electricity grid.

Greenhouse gas savings

Hydro power is a zero-emission electricity source. One megawatt hour of hydro-derived electricity avoids approximately one tonne of CO2.

In Australia

With a long history of development in Tasmania and the Snowy Mountains Scheme in NSW, hydro delivers the majority of Australia’s renewable energy. There are more than 100 hydroelectricity stations with the capacity to produce 8,178 megawatts of electricity generation. Around the nation, another 176 megawatts in new capacity is either committed or currently under construction.

Australia’s major hydro electricity schemes are in:

• Tasmania
• The Snowy Mountains
• North East Victoria
• Queensland and
• The Ord River in Western Australia.

Potential

Opportunities still exist in Australia for small hydro electricity generators on streams, in town water supplies and other places where there are regular water flows. The costs of producing electricity from
small hydro where a new dam is not needed are similar to those of wind generation. A market mechanism is required to ensure further roll out of small hydro.

Global view

Hydroelectricity is the largest renewable electricity source: it makes up 16 per cent of the world’s electricity. Currently there are over 800,000 megawatts of installed hydro electricity worldwide producing around 3 million gigawatt hours of electricity. The top four countries for hydro electricity are:

• USA
• China
• Brazil
• Canada

Current Issues

The ongoing drought in Australia is having an impact on hydro schemes across the country. Although generators of hydroelectricity have employed water conservation and recycling measures where possible to mitigate the reduction of water in dams and rivers, power generation has been affected.