Fact Sheet 6

RENEWABLE FORMS OF ENERGY

Solar

There are two main ways of using solar energy to produce electricity. These are through the use of solar cells and solar thermal technology. Using solar technologies to generate electricity is, at present, more expensive than using coal-fired power stations, but it produces much less pollution.

Solar cells are photovoltaic cells that turn light into electricity. Solar cells are used in three main ways. They are used in small electrical items, like calculators, and for remote area power supplies, like telephones and space satellites. They are also used on a larger scale to supply electricity through energy authorities such as energex and Ergon.

Solar cells are used to a limited extent in the development of solar-powered vehicles. Solar thermal technology uses heat gained directly from sunlight. The best known use of this technology is in solar water heating. Solar thermal electric generating plants use reflectors to collect heat energy to make steam which drives a turbine that produces electricity. Australia is in an ideal position to develop and use solar energy. Some areas in central and western Queensland are among the best sites in the world to develop large scale solar electric generating plants.

Biomass

All plant and animal matter is called biomass. It is the mass of biological matter on earth. We can get (biomass) energy:

• Directly from plants, for example burning wood for cooking and heating.
• Indirectly from plants, for example turning it into a liquid (alcohol such as ethanol) or gas (biogas) fuel.
• Indirectly from animal waste, for example biogas (mainly methane gas) from sewage and manure.

An increasing number of renewable energy projects using biomass has been developed. Most of these use waste products from agriculture, so they solve a waste disposal problem and, at the same time, create energy for use in homes, farms and factories.

Logan City Council collects biogas from a landfill site at Browns Plains, and uses it to generate electricity. Four companies in Ipswich are working together to use energy from landfill biogas. The biogas will be processed and piped to nearby Swanbank Power Station.

Biogas can also be produced from livestock manure and human sewage. Farms where animals graze and sewage plants are ideal places to produce energy from biogas. Waste peelings from food processing plants can also be used to produce biogas.

An example of agricultural waste being used to produce electricity is the recent Mackay Sugar Cooperative Association bagasse project. Bagasse (solid waste from sugar production) from four mills will be processed and used instead of coal to produce electricity.

Hydroelectric

Hydroelectricity is produced from falling water. The movement of the water spins turbines which generate electricity.

Places with high rainfall and steep mountains are ideal for hydroelectricity. Canada, Brazil and New Zealand produce most of their electricity this way. In Australia about 8 per cent of electricity is produced from hydroelectricity. Most of this is from the Snowy Mountains Scheme in New South Wales. Queensland has two hydroelectric power stations in the Barron Gorge and Kareeya in far north Queensland.

Most hydroelectricity projects require the building of large dams on rivers, which can be very expensive. When large dams are built the flow of the dammed river is changed radically and large areas of land are flooded, including wildlife habitats and farming land.

Because of the environmental impact of traditional hydroelectric schemes, there has been increasing interest in alternative hydro schemes. Pumped storage systems can be installed on existing dams. There is a pumped storage hydroelectric power station at Wivenhoe Dam, west of Brisbane.

Run-of-river hydroelectric schemes cause less environmental damage. Large dams do not need to be built, as the run-of-river schemes divert only part of the river through a turbine.

Wind

While wind-generated electricity does not cause air pollution, it does cost more to produce than electricity generated from coal.

Wind pumps and generators have been used in remote areas of Australia and in other countries around the world for many years. More recently, wind turbo-generators on wind farms have been providing electricity for cities and towns in more than a dozen countries. The United States of America and Denmark produce most of the world’s wind-generated electricity. Australia has some small wind farms. The largest of these is at Esperance in Western Australia.

In Queensland, wind farms operate at Atherton Tablelands and Thursday Island.

A large wind turbo generator needs a minimum annual average windspeed of about 25 km/h. Sites need to be clear of tall vegetation and are often on prominent hills and headlands or in coastal areas. The southern states in Australia are in a good position to use wind generators because of a strong wind called the ‘roaring forties’ that blows across the south of the continent.

Large wind generators can be more than 110 metres tall with blades spanning 130 metres. They can sometimes make a low-frequency sound that cannot be heard by humans, but which can rattle windows. Wind farms can be a danger to migrating birds flying at night and can cause TV and radio interference in nearby homes. Because of their size, some people think wind generators are ugly and spoil the scenery, however in some places they are a tourist attraction.

Available as:

PDF – Fact Sheet 6

Disclaimer. Copyright The State of Queensland (Department of Education) 2000