Energy sources
SOLAR
What is it?
Solar power is energy from the sun. The sun is 150 million kilometres away, but it is over 1 million degrees Celsius at the core. If we could harness it, there is enough solar power reaching the earth to provide all of our energy needs 10,000 times over!
Since almost the beginning of man, solar power has been used for drying clothes and food. It was not until 1954 however, that scientists in the United States produced electricity from the sun - to power satellites in space. They invented photoelectric (or photovoltaic) panels (or cells), which capture the sun's energy and turn it into electricity.
Solar power is also used in many countries to heat water - you or someone you know may have a solar hot-water heater on the roof at home.
How does it work?
Photovoltaic cells are made up like a sandwich - two layers of silicon with chemicals in the middle. Sunlight is used to charge electrons in the chemicals. The energised electrons move through the cell and flow into a wire, creating an electrical current.
Solar water heaters use the sun's rays to heat your water. They basically consist of solar collector panels and a storage tank.
The most common type, has panels covered by a special toughened glass that sunlight can easily pass through. The solar radiation hits an absorber plate that has a number of vertical tubes. Cold water from the mains supply or an anti-freeze fluid, enters the panels at the bottom and is heated by the sun.
A solar water heater can't provide 100% of your hot-water needs year-round as there may be several consecutive overcast days when the sun doesn't provide enough radiation to sufficiently heat your water. That's why all solar water systems have an electric or gas booster in their tanks to help when there's not enough sun.
Advantages
Solar energy is free. It is also a renewable source of energy - it will never run out and Australia's sunny climate is well suited for solar power. Solar energy produces no greenhouse gases and is excellent for remote areas that are not connected to the main electricity grid. Solar power can even be made very small for items such as calculators and watches.
Disadvantages
While solar energy is free, it is very expensive to harness and produce power. It doesn't work at night, and can be very unpredictable as some days have little or no sun.
Use in Australia and around the world
The largest solar power farm in Australia (and the Southern Hemisphere) is at Singleton in New South Wales. It produces 400 kW of electricity - enough to power 100 homes. It is operated by Energy Australia, and covers 2.75 hectares - which is about 5 football fields!
The annual energy production from the solar farm is approximately 500,000 kWh, preventing the release into the atmosphere of around 500 tonnes of greenhouse gases. Solar power is used throughout the world, but its high cost stops it from being more widely used. It is most often used in remote locations, where regular electricity supply is not available. It is also used in space to power satellites.
