Sources of Energy

Solar Energy

Solar energy is light and heat energy from the sun. Solar cells convert sunlight into electrical energy. Thermal collectors convert sunlight into heat energy. Solar technologies are used in watches, calculators, water pumps, space satellites, for heating water, and supplying clean electricity to the power grid. There is enough solar radiation striking the surface of the earth to provide all of our energy needs.

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.

Wind Energy

Moving air turns the blades of large windmills or generators to make electricity, or to pump water out of the ground. A high wind speed is needed to power wind generators effectively. While wind generators don't produce any greenhouse gas emissions they may cause vibrations, noise and visual pollution.

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.

Tidal/Wave Energy

If a dam or barrage is built across a river mouth or inlet, electricity can be obtained by the flow of water through turbines in the dam as the tide rises and falls. The movement of waves can also drive air turbines to make electricity. Although tidal and wave energy don't produce pollution, they can cause other environmental problems.

Biomass Energy

Biomass is plant and animal material that can be used for energy. This includes using wood from trees, waste from other plants (for example, bagasse from sugar cane) and manure from livestock. Biomass can be used to generate electricity, light, heat, motion and fuel. Converting biomass energy into useable energy has many environmental benefits. It uses waste materials that are usually dumped, and uses up methane (a greenhouse gas). Fuels such as ethanol can be made from biomass and used as an alternative to petrol to power motor cars.

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. o 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 Energy

Fast-flowing water released from dams in mountainous areas can turn water turbines to produce electricity. While it doesn't cause pollution, there are many other environmental impacts to consider. Ecosystems may be destroyed, cultural sites may be flooded and sometimes people need to be resettled.