- 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.
There are also impacts on fish breeding, loss of wildlife habitat and changes
in water flow of rivers.
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.
- Geothermal Energy:
Geothermal energy uses heat energy from beneath the surface of the earth.
Some of this heat finds its way to the surface in the form of hot springs
or geysers. Other schemes tap the heat energy by pumping water through
hot dry rocks several kilometres beneath the earth's surface. Geothermal
energy is used for the generation of electricity and for space and water
heating in a small number of countries.